operator < method
Implementation
bool operator <(Object o) => valueNumber == null ||
(o is! FhirInteger64 && o is! BigInt) ||
(o is FhirInteger64 && o.valueNumber == null)
? throw InvalidTypes<FhirInteger64>(
'One of the values is not valid or null\n'
'This number is: ${toString()}, compared number is $o')
: o is FhirInteger64
? valueNumber! < o.valueNumber!
: valueNumber! < (o as BigInt);