code: def unwrap(self, value, session=None):
          ''' Unwraps the elements of ``value`` using ``SetField.item_type`` and
              returns them in a set'''
          self.validate_unwrap(value)
          return set([self.item_type.unwrap(v, session=session) for v in value]f unwrap(self, value, session=None):
          ''' Unwraps the elements of ``value`` using ``SetField.item_type`` and
              returns them in a set'''
          self.validate_unwrap(value)
          return set([self.item_type.unwrap(v, session=session) for v in value])
docs: Unwraps the elements of ``value`` using ``SetField.item_type`` and
              returns them in a set