checkIsDateBefore static method
Check if the param fromDate is before the param toDate.
Both fromDate and toDate need be a object of DateTime or LunarDateTime.
If passing another type the result will return null.
Implementation
static bool? checkIsDateBefore(
{required dynamic fromDate, required dynamic toDate}) {
var r = _rangeDate(fromDate, toDate);
return (r == null) ? null : (r > 0);
}