code: def compile_timeoper(rule):
      
      if isinstance(rule.value, (datetime.datetime, datetime.timedelta)):
          return rule
      if isinstance(rule, NumberRule):
          return compile_timedelta(rule)
      if isinstance(rule, ConstantRule):
          try:
              return compile_datetime(rule)
          except ValueError:
              pass
          try:
              return compile_timedelta(rule)
          except ValueError:
              pass
      raise ValueError("Wrong time operation constant '{}'".format(rule))
docs: Compiler helper method: attempt to compile constant into object representing
      datetime or timedelta object to enable relations and thus simple comparisons
      using Python operators.