docs: def _is_valid_duration(self, inpt, metadata):
          """Checks if input is a valid Duration"""
          # NEED TO ADD CHECKS FOR OTHER METADATA, LIKE MINIMUM, MAXIMUM, ETC.
          from dlkit.abstract_osid.calendaring.primitives import Duration as abc_duration
          if isinstance(inpt, abc_duration):
              return True
          else:
              return False