function
A function call expression consisting of a referential identifier followed by a parenthesized argument list. Resolves to a named function definition in the current or an included library.
Examples
Built-in function call
AgeInYears()
User-defined function call
"CalculateBMI"(weight, height)
Library-qualified function call
FHIRHelpers.ToInterval(Encounter.period)
EBNF
function
: referentialIdentifier '(' paramList? ')'
;