define "Initial Population":
  exists "Qualifying Encounter During Day Of Measurement Period" QualifyingEncounter
    where "AgeInYearsAt"(date from start of QualifyingEncounter.period) >= 18

define "Denominator":
  "Initial Population"

define "Denominator Exclusions":
  Hospice."Has Hospice Services"
    or PalliativeCare."Has Palliative Care in the Measurement Period"
    or "Is Pregnant During Measurement Period"

define "Denominator Exceptions":
  exists "Medical Reason For Not Documenting A Follow Up Plan For Low Or High BMI"
    or exists "Medical Reason Or Patient Reason For Not Performing BMI Exam"

define "Numerator":
  exists "High BMI And Follow Up Provided"
    or exists "Low BMI And Follow Up Provided"
    or "Has Normal BMI"

define "Has Hospice Services":
  exists ((([USQualityCore.Encounter: "Encounter Inpatient"]).isEncounterPerformed()) InpatientEncounter
      where (InpatientEncounter.hospitalization.dischargeDisposition ~ "Discharge to home for hospice care (procedure)"
          or InpatientEncounter.hospitalization.dischargeDisposition ~ "Discharge to healthcare facility for hospice care (procedure)"
      )
        and InpatientEncounter.period ends during day of "Measurement Period"
  )
    or exists ((([USQualityCore.Encounter: "Hospice Encounter"]).isEncounterPerformed()) HospiceEncounter
        where HospiceEncounter.period overlaps day of "Measurement Period"
    )
    // TODO: Shouldn't need to specify a code path here (see https://jira.hl7.org/browse/FHIR-53941)
    or exists ((([USQualityCore.ObservationScreeningAssessment: code ~ "Hospice care [Minimum Data Set]"]).isAssessmentPerformed()) HospiceAssessment
        where HospiceAssessment.value ~ "Yes (qualifier value)"
          and HospiceAssessment.effective.toInterval() overlaps day of "Measurement Period"
    )
    or exists ((([USQualityCore.ServiceRequest: "Hospice Care Ambulatory"]).isInterventionOrder()) HospiceOrder
        where HospiceOrder.authoredOn during day of "Measurement Period"
    )
    or exists ((([USQualityCore.Procedure: "Hospice Care Ambulatory"]).isInterventionPerformed()) HospicePerformed
        where HospicePerformed.performed.toInterval() overlaps day of "Measurement Period"
    )
    // TODO: Consider whether to keep this as the union of Problems and EncounterDiagnosis
    or exists ((([FHIR.Condition: "Hospice Diagnosis"]).verified()) HospiceCareDiagnosis
        where HospiceCareDiagnosis.prevalenceInterval() overlaps day of "Measurement Period"
    )

define "Has Palliative Care in the Measurement Period":
  // TODO: Shouldn't need to specify a code path here (see https://jira.hl7.org/browse/FHIR-53941)
  exists ((([USQualityCore.ObservationScreeningAssessment: code ~ "Functional Assessment of Chronic Illness Therapy - Palliative Care Questionnaire (FACIT-Pal)"]).isAssessmentPerformed()) PalliativeAssessment
      where PalliativeAssessment.effective.toInterval() overlaps day of "Measurement Period"
  )
    // TODO: Consider whether to keep this as the union of the problems and encounter diagnosis list? Anything enforced by the profiles that is expected but isn't stated here?
    or exists ((([FHIR.Condition: "Palliative Care Diagnosis"]).verified()) PalliativeDiagnosis
        where PalliativeDiagnosis.prevalenceInterval() overlaps day of "Measurement Period"
    )
    or exists ((([USQualityCore.Encounter: "Palliative Care Encounter"]).isEncounterPerformed()) PalliativeEncounter
        where PalliativeEncounter.period overlaps day of "Measurement Period"
    )
    or exists ((([USQualityCore.Procedure: "Palliative Care Intervention"]).isInterventionPerformed()) PalliativeIntervention
        where PalliativeIntervention.performed.toInterval() overlaps day of "Measurement Period"
    )

define "SDE Sex":
  case
    when Patient.sex() = '248153007' then "Male (finding)"
    when Patient.sex() = '248152002' then "Female (finding)"
    else null
  end

define "SDE Payer":
  [USQualityCore.Coverage: type in "Payer Type"] Payer
    return {
      code: Payer.type,
      period: Payer.period
    }

define "SDE Ethnicity":
  (Patient.ethnicity()) E
    return Tuple {
      codes: { E.ombCategory } union E.detailed,
      display: E.text
    }

define "SDE Race":
  (Patient.race()) R
    return Tuple {
      codes: R.ombCategory union R.detailed,
      display: R.text
    }

define "SDE Sex":
  SDE."SDE Sex"

define "BMI During Measurement Period":
  ( ( [USCore.BMIProfile] ).isObservationBMI ( ) ) BMI
    where BMI.value > 0 'kg/m2'
      and BMI.effective.toInterval ( ) during day of "Measurement Period"

define "Documented High BMI During Measurement Period":
  "BMI During Measurement Period" BMI
    where BMI.value >= 25 'kg/m2'

define "High BMI Interventions Ordered":
  ( ( [ServiceRequest: "Follow Up for Above Normal BMI"]
      union [ServiceRequest: "Referrals Where Weight Assessment May Occur"]
      union [MedicationRequest: "Medications for Above Normal BMI"] ) HighInterventionsOrdered
      where HighInterventionsOrdered.reasonCode in "Overweight or Obese"
        or ( exists ( [ConditionProblemsHealthConcerns: "Overweight or Obese"]
            union [ConditionEncounterDiagnosis: "Overweight or Obese"] ) OverweightObese
            where OverweightObese.onset.toInterval ( ) starts before or on day of HighInterventionsOrdered.authoredOn
        )
  )

define "High BMI Interventions Performed":
  ( [Procedure: "Follow Up for Above Normal BMI"] HighInterventionsPerformed
      where HighInterventionsPerformed.reasonCode in "Overweight or Obese"
        or ( exists [ConditionProblemsHealthConcerns: "Overweight or Obese"] OverweightObese
            where OverweightObese.prevalenceInterval ( ) starts before or on day of start of HighInterventionsPerformed.performed.toInterval ( )
              and not ( OverweightObese.prevalenceInterval ( ) ends before day of start of HighInterventionsPerformed.performed.toInterval ( ) )
        )
  )

define "High BMI And Follow Up Provided":
  "Documented High BMI During Measurement Period" HighBMI
    with ( "High BMI Interventions Ordered"
      union "High BMI Interventions Performed" ) HighBMIInterventions
      such that Coalesce(HighBMIInterventions.performed.toInterval(), HighBMIInterventions.authoredOn.toInterval()) starts during day of "Measurement Period"

define "Documented Low BMI During Measurement Period":
  "BMI During Measurement Period" BMI
    where BMI.value < 18.5 'kg/m2'

define "Low BMI Interventions Ordered":
  ( ( [ServiceRequest: "Follow Up for Below Normal BMI"]
      union [ServiceRequest: "Referrals Where Weight Assessment May Occur"]
      union [MedicationRequest: "Medications for Below Normal BMI"] ) LowInterventionsOrdered
      where LowInterventionsOrdered.reasonCode in "Underweight"
        or ( exists ( [ConditionProblemsHealthConcerns: "Underweight"]
            union [ConditionEncounterDiagnosis: "Underweight"] ) UnderweightDiagnosis
            where UnderweightDiagnosis.onset.toInterval ( ) starts before or on day of LowInterventionsOrdered.authoredOn
              and LowInterventionsOrdered.authoredOn during day of "Measurement Period"
        )
  )

define "Low BMI Interventions Performed":
  ( [Procedure: "Follow Up for Below Normal BMI"] LowInterventionsPerformed
      where LowInterventionsPerformed.reasonCode in "Underweight"
        and LowInterventionsPerformed.status = 'completed'
        or ( exists [ConditionProblemsHealthConcerns: "Underweight"] UnderweightDiagnosis
            where ( UnderweightDiagnosis.isHealthConcern ( ) )
              and UnderweightDiagnosis.prevalenceInterval ( ) starts before or on day of start of LowInterventionsPerformed.performed.toInterval ( )
              and LowInterventionsPerformed.performed.toInterval ( ) during day of "Measurement Period"
              and not ( UnderweightDiagnosis.prevalenceInterval ( ) ends before day of start of LowInterventionsPerformed.performed.toInterval ( ) )
        )
  )

define "Low BMI And Follow Up Provided":
  ( "Documented Low BMI During Measurement Period" LowBMI
      with ( "Low BMI Interventions Ordered"
        union "Low BMI Interventions Performed" ) LowBMIInterventions
        such that Coalesce(LowBMIInterventions.performed.toInterval(), LowBMIInterventions.authoredOn.toInterval()) starts during day of "Measurement Period"
  )

define "Has Normal BMI":
  exists ( "BMI During Measurement Period" BMI
      where BMI.value >= 18.5 'kg/m2'
        and BMI.value < 25 'kg/m2'
  )
    and not ( exists "Documented High BMI During Measurement Period"
        or exists "Documented Low BMI During Measurement Period"
    )

define "Numerator":
  exists "High BMI And Follow Up Provided"
    or exists "Low BMI And Follow Up Provided"
    or "Has Normal BMI"

define "Qualifying Encounter During Day Of Measurement Period":
  [Encounter: "Encounter to Evaluate BMI"] BMIEncounter
    where BMIEncounter.period during day of "Measurement Period"
      and BMIEncounter.class !~ "virtual"
      and BMIEncounter.status = 'finished'

define "Initial Population":
  exists "Qualifying Encounter During Day Of Measurement Period" QualifyingEncounter
    where "AgeInYearsAt"(date from start of QualifyingEncounter.period) >= 18

define "Denominator":
  "Initial Population"

define "SDE Payer":
  SDE."SDE Payer"

define "SDE Ethnicity":
  SDE."SDE Ethnicity"

define "Is Pregnant During Measurement Period":
  exists ( ( [ConditionProblemsHealthConcerns: "Pregnancy or Other Related Diagnoses"]
      union [ConditionEncounterDiagnosis: "Pregnancy or Other Related Diagnoses"] ) PregnancyDiagnosis
      where PregnancyDiagnosis.onset.toInterval ( ) overlaps day of "Measurement Period"
  )
    or exists ( [USCore.ObservationPregnancyStatusProfile] PregnantObservation
        where PregnantObservation.effective.toInterval ( ) overlaps day of "Measurement Period"
          and PregnantObservation.status in { 'final', 'amended', 'corrected' }
          and ( PregnantObservation.value in "Pregnancy or Other Related Diagnoses" )
    )

define "Denominator Exclusions":
  Hospice."Has Hospice Services"
    or PalliativeCare."Has Palliative Care in the Measurement Period"
    or "Is Pregnant During Measurement Period"

define "SDE Race":
  SDE."SDE Race"

define "Medical Reason For Not Documenting A Follow Up Plan For Low Or High BMI":
  ( ( [ServiceNotRequested: "Referrals Where Weight Assessment May Occur"]
      union [ServiceNotRequested: "Follow Up for Above Normal BMI"]
      union [ServiceNotRequested: "Follow Up for Below Normal BMI"] ) NoBMIFollowUp
      with "Qualifying Encounter During Day Of Measurement Period" QualifyingEncounter
        such that NoBMIFollowUp.authoredOn same day as start of QualifyingEncounter.period
      where NoBMIFollowUp.status ~ 'completed'
        and NoBMIFollowUp.reasonRefused ( ) in "Medical Reason"
  )
    union ( ( [MedicationNotRequested: "Medications for Above Normal BMI"]
        union [MedicationNotRequested: "Medications for Below Normal BMI"] ) NoBMIFollowUp
        with "Qualifying Encounter During Day Of Measurement Period" QualifyingEncounter
          such that NoBMIFollowUp.authoredOn same day as start of QualifyingEncounter.period
        where NoBMIFollowUp.status ~ 'completed'
          and NoBMIFollowUp.reasonCode in "Medical Reason"
    )

define "Medical Reason Or Patient Reason For Not Performing BMI Exam":
  [ObservationCancelled: "Body mass index (BMI) [Ratio]"] NoBMI
    with "Qualifying Encounter During Day Of Measurement Period" QualifyingEncounter
      such that NoBMI.effective.toInterval ( ) ends same day as start of QualifyingEncounter.period
    where ( NoBMI.notDoneReason ( ) in "Patient Declined"
        or NoBMI.notDoneReason ( ) in "Medical Reason"
    )

define "Denominator Exceptions":
  exists "Medical Reason For Not Documenting A Follow Up Plan For Low Or High BMI"
    or exists "Medical Reason Or Patient Reason For Not Performing BMI Exam"

define fluent function isObservationBMI(Obs List<BMIProfile>):
  Obs O
    where O.status in { 'final', 'amended', 'corrected' }

//Encounter, Performed
//General usage unless required otherwise by measure intent (e.g., follow-up encounters)
define fluent function isEncounterPerformed(Enc List<FHIR.Encounter>):
  Enc E
    where E.status = 'finished'

//Assessment, Performed
define fluent function isAssessmentPerformed(Obs List<ObservationScreeningAssessment>):
  Obs O
    where O.status in { 'final', 'amended', 'corrected' }

//Intervention, Order
define fluent function isInterventionOrder(ServiceRequest List<FHIR.ServiceRequest>):
  ServiceRequest S
    where S.status in { 'active', 'completed' }
      and S.intent in {'order', 'original-order', 'reflex-order', 'filler-order', 'instance-order'}

//Intervention, Performed
define fluent function isInterventionPerformed(Proc List<FHIR.Procedure>):
  Proc P
    where P.status ~ 'completed'

/*
@description: Returns the single extension (if present) on the given resource with the specified url.
@comment: This function uses singleton from to ensure that a run-time exception is thrown if there
is more than one extension on the given resource with the specified url.
*/
define fluent function ext(domainResource DomainResource, url String):
  singleton from domainResource.exts(url)

/*
@description: Returns any extensions defined on the given resource with the specified url
*/
define fluent function exts(domainResource DomainResource, url String):
  domainResource.extension E
    where E.url = url
    return E

/*
@description: Normalizes a value that is a choice of timing-valued types to an equivalent interval
@comment: Normalizes a choice type of FHIR.dateTime, FHIR.Period, FHIR.Timing, FHIR.instance, FHIR.string, FHIR.Age, or FHIR.Range types
to an equivalent interval. This selection of choice types is a superset of the majority of choice types that are used as possible
representations for timing-valued elements in FHIR, allowing this function to be used across any resource.

The input can be provided as a dateTime, Period, Timing, instant, string, Age, or Range.
The intent of this function is to provide a clear and concise mechanism to treat single
elements that have multiple possible representations as intervals so that logic doesn't have to account
for the variability. More complex calculations (such as medication request period or dispense period
calculation) need specific guidance and consideration. That guidance may make use of this function, but
the focus of this function is on single element calculations where the semantics are unambiguous.
If the input is a dateTime, the result a DateTime Interval beginning and ending on that dateTime.
If the input is a Period, the result is a DateTime Interval.
If the input is a Timing, an error is raised indicating a single interval cannot be computed from a Timing.
If the input is an instant, the result is a DateTime Interval beginning and ending on that instant.
If the input is a string, an error is raised indicating a single interval cannot be computed from a string.
If the input is an Age, the result is a DateTime Interval beginning when the patient was the given Age,
and ending immediately prior to when the patient was the given Age plus one year.
If the input is a Range, the result is a DateTime Interval beginning when the patient was the Age given
by the low end of the Range, and ending immediately prior to when the patient was the Age given by the
high end of the Range plus one year.

NOTE: Due to the
complexity of determining a single interval from a Timing or String type, this function will throw a run-time exception if it is used
with a Timing or String.
*/
define fluent function toInterval(choice Choice<FHIR.dateTime, FHIR.Period, FHIR.Timing, FHIR.instant, FHIR.string, FHIR.Age, FHIR.Range>):
  case
    when choice is FHIR.dateTime then
      Interval[FHIRHelpers.ToDateTime(choice as FHIR.dateTime), FHIRHelpers.ToDateTime(choice as FHIR.dateTime)]
    when choice is FHIR.Period then
      FHIRHelpers.ToInterval(choice as FHIR.Period)
    when choice is FHIR.instant then
      Interval[FHIRHelpers.ToDateTime(choice as FHIR.instant), FHIRHelpers.ToDateTime(choice as FHIR.instant)]
    when choice is FHIR.Age then
      Interval[FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity(choice as FHIR.Age),
        FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity(choice as FHIR.Age) + 1 year)
    when choice is FHIR.Range then
      Interval[FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity((choice as FHIR.Range).low),
        FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity((choice as FHIR.Range).high) + 1 year)
    when choice is FHIR.Timing then
      Message(null as Interval<DateTime>, true, 'NOT_IMPLEMENTED', 'Error', 'Calculation of an interval from a Timing value is not supported')
    when choice is FHIR.string then
      Message(null as Interval<DateTime>, true, 'NOT_IMPLEMENTED', 'Error', 'Calculation of an interval from a String value is not supported')
    else
      null as Interval<DateTime>
  end

/*
@description: Returns an interval representing the normalized prevalence period of a given Condition resource.
@comment: Uses the toInterval and toAbatementInterval functions to determine the widest potential interval from
onset to abatement as specified in the given Condition.
*/
define fluent function prevalenceInterval(condition Condition):
if condition.clinicalStatus ~ "active"
  or condition.clinicalStatus ~ "recurrence"
  or condition.clinicalStatus ~ "relapse" then
  Interval[start of condition.onset.toInterval(), end of condition.abatementInterval()]
else
  (end of condition.abatementInterval()) abatementDate
    return 
	  if abatementDate is null then
        Interval[start of condition.onset.toInterval(), abatementDate)
      else
        Interval[start of condition.onset.toInterval(), abatementDate]

/*
@description: Returns an interval representing the normalized Abatement of a given Condition resource.
@comment: @comment: If the abatement element of the Condition is represented as a DateTime, the result
is an interval beginning and ending on that DateTime.
If the abatement is represented as a Quantity, the quantity is expected to be a calendar-duration and is interpreted as the age of the patient. The
result is an interval from the date the patient turned that age to immediately before one year later.
If the abatement is represented as a Quantity Interval, the quantities are expected to be calendar-durations and are interpreted as an age range during
which the abatement occurred. The result is an interval from the date the patient turned the starting age of the quantity interval, and ending immediately
before one year later than the date the patient turned the ending age of the quantity interval.

NOTE: Due to the complexity of determining an interval from a String, this function will throw
a run-time exception if used with a Condition instance that has a String as the abatement value.
*/
define fluent function abatementInterval(condition Condition):
  if condition.abatement is FHIR.dateTime then
    Interval[FHIRHelpers.ToDateTime(condition.abatement as FHIR.dateTime), FHIRHelpers.ToDateTime(condition.abatement as FHIR.dateTime)]
  else if condition.abatement is FHIR.Period then
    FHIRHelpers.ToInterval(condition.abatement as FHIR.Period)
  else if condition.abatement is FHIR.string then
    Message(null as Interval<DateTime>, true, 'NOT_IMPLEMENTED', 'Error', 'Calculation of an interval from a String value is not supported')
  else if condition.abatement is FHIR.Age then
    Interval[FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity(condition.abatement as FHIR.Age),
      FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity(condition.abatement as FHIR.Age) + 1 year)
  else if condition.abatement is FHIR.Range then
    Interval[FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity((condition.abatement as FHIR.Range).low),
      FHIRHelpers.ToDate(Patient.birthDate) + FHIRHelpers.ToQuantity((condition.abatement as FHIR.Range).high) + 1 year)
  else if condition.abatement is FHIR.boolean then
    Interval[end of condition.onset.toInterval(), condition.recordedDate)
  else 
    null

/*
@description: Returns the single extension (if present) on the given element with the specified url.
@comment: This function uses singleton from to ensure that a run-time exception is thrown if there
is more than one extension on the given element with the specified url.
*/
define fluent function ext(element Element, url String):
  singleton from element.exts(url)

/*
@description: Returns any extensions defined on the given element with the specified url.
*/
define fluent function exts(element Element, url String):
  element.extension E
    where E.url = url
    return E

/*
@description: Returns conditions in the given list that either have no verification status or have a verification status of confirmed, unconfirmed, provisional, or differential
*/
define fluent function verified(conditions List<FHIR.Condition>):
  conditions C
    where C.verificationStatus is not null implies
      (C.verificationStatus ~ "confirmed"
        or C.verificationStatus ~ "unconfirmed"
        or C.verificationStatus ~ "provisional"
        or C.verificationStatus ~ "differential"
      )

/*
@description: Returns the sex element as defined for the USCore patient profile
*/
define fluent function sex(patient Patient):
  patient.ext('http://hl7.org/fhir/us/core/StructureDefinition/us-core-sex').value as FHIR.code

/*
@description: Returns true if the given condition is a health concern
*/
define fluent function isHealthConcern(condition FHIR.Condition):
  exists (
    condition.category C
      where C ~ "health-concern"
  )

define fluent function ethnicity(patient Patient):
  (patient.ext('http://hl7.org/fhir/us/core/StructureDefinition/us-core-ethnicity')) E
    return {
      ombCategory: E.ext('ombCategory').value as FHIR.Coding,
      detailed: (E.exts('detailed')) d return d.value as FHIR.Coding,
      text: E.ext('text').value as FHIR.string
    }

define fluent function race(patient Patient):
  (patient.ext('http://hl7.org/fhir/us/core/StructureDefinition/us-core-race')) E
    return {
      ombCategory: (E.exts('ombCategory')) o return o.value as FHIR.Coding,
      detailed: (E.exts('detailed')) d return d.value as FHIR.Coding,
      text: E.ext('text').value as FHIR.string
    }

define function ToString(value string): value.value

define function ToString(value uri): value.value

define function ToString(value ObservationStatus): value.value

/*
@description: Converts the given FHIR [Quantity](https://hl7.org/fhir/datatypes.html#Quantity) 
value to a CQL Quantity
@comment: If the given quantity has a comparator specified, a runtime error is raised. If the given quantity
has a system other than UCUM (i.e. `http://unitsofmeasure.org`) or CQL calendar units (i.e. `http://hl7.org/fhirpath/CodeSystem/calendar-units`)
an error is raised. For UCUM to calendar units, the `ToCalendarUnit` function is used.
@seealso: ToCalendarUnit
*/
define function ToQuantity(quantity FHIR.Quantity):
    case
        when quantity is null then null
        when quantity.value is null then null
        when quantity.comparator is not null then
            Message(null, true, 'FHIRHelpers.ToQuantity.ComparatorQuantityNotSupported', 'Error', 'FHIR Quantity value has a comparator and cannot be converted to a System.Quantity value.')
        when quantity.system is null or quantity.system.value = 'http://unitsofmeasure.org'
              or quantity.system.value = 'http://hl7.org/fhirpath/CodeSystem/calendar-units' then
            System.Quantity { value: quantity.value.value, unit: ToCalendarUnit(Coalesce(quantity.code.value, quantity.unit.value, '1')) }
        else
            Message(null, true, 'FHIRHelpers.ToQuantity.InvalidFHIRQuantity', 'Error', 'Invalid FHIR Quantity code: ' & quantity.unit.value & ' (' & quantity.system.value & '|' & quantity.code.value & ')')
    end

/*
@description: Converts a UCUM definite duration unit to a CQL calendar duration
unit using conversions specified in the [quantities](https://cql.hl7.org/02-authorsguide.html#quantities) 
topic of the CQL specification.
@comment: Note that for durations above days (or weeks), the conversion is understood to be approximate
*/
define function ToCalendarUnit(unit System.String):
    case unit
        when 'ms' then 'millisecond'
        when 's' then 'second'
        when 'min' then 'minute'
        when 'h' then 'hour'
        when 'd' then 'day'
        when 'wk' then 'week'
        when 'mo' then 'month'
        when 'a' then 'year'
        else unit
    end

define function ToDateTime(value dateTime): value.value

/*
@description: Converts the given [Period](https://hl7.org/fhir/datatypes.html#Period)
value to a CQL DateTime Interval
@comment: If the start value of the given period is unspecified, the starting
boundary of the resulting interval will be open (meaning the start of the interval
is unknown, as opposed to interpreted as the beginning of time).
*/
define function ToInterval(period FHIR.Period):
    if period is null then
        null
    else
        if period."start" is null then
            Interval(period."start".value, period."end".value]
        else
            Interval[period."start".value, period."end".value]

define function ToDateTime(value instant): value.value

define function ToDate(value date): value.value

/*
@description: Converts the given FHIR [CodeableConcept](https://hl7.org/fhir/datatypes.html#CodeableConcept) value to a CQL Concept.
*/
define function ToConcept(concept FHIR.CodeableConcept):
    if concept is null then
        null
    else
        System.Concept {
            codes: concept.coding C return ToCode(C),
            display: concept.text.value
        }

/*
@description: Converts the given FHIR [Coding](https://hl7.org/fhir/datatypes.html#Coding) value to a CQL Code.
*/
define function ToCode(coding FHIR.Coding):
    if coding is null then
        null
    else
        System.Code {
          code: coding.code.value,
          system: coding.system.value,
          version: coding.version.value,
          display: coding.display.value
        }

define function ToString(value ProcedureStatus): value.value

define function ToString(value EncounterStatus): value.value

define function ToString(value ServiceRequestStatus): value.value

define function ToString(value ServiceRequestIntent): value.value

define function ToString(value MedicationRequestStatus): value.value

/*
@description: Returns the value of the recorded extension for a Medication Administration Not Done
*/
define fluent function reasonRefused(serviceNotRequested ServiceNotRequested):
  serviceNotRequested.ext('http://fhir.org/guides/astp/us-quality-core/StructureDefinition/us-quality-core-doNotPerformReason').value as FHIR.CodeableConcept

/*
@description: Returns the notDoneReason for an ObservationCancelled
*/
define fluent function notDoneReason(observationCancelled ObservationCancelled):
  observationCancelled.ext('http://fhir.org/guides/astp/us-quality-core/StructureDefinition/us-quality-core-notDoneReason').value as FHIR.CodeableConcept