Function evaluation 

pub async fn evaluation<'a, 'b>(
    x_fhir_query: &str,
    values: Vec<&'a dyn MetaValue>,
    config: Arc<Config<'b>>,
) -> Result<String, OperationOutcomeError>
where
    'a: 'b,

Evaluates FHIRPath expressions embedded in an x-fhir-query string.

Replaces each FHIRPath expression found in the query with the evaluated string representation of its result.

Errors

Returns an [OperationOutcomeError] if:

• the embedded FHIRPath expression is empty,
• FHIRPath evaluation fails,
• a result value cannot be converted into a string representation.