code: def _call_command(self, name, *args, **kwargs):
          
          if self.dynamic_version_of is None:
              raise ImplementationError('The main version of a dynamic field cannot accept commands')
          try:
              result = super(DynamicFieldMixin, self)._call_command(name, *args, **kwargs)
          except:
              raise
          else:
              if name in self.available_modifiers and name not in ('delete', 'hdel'):
                  self._inventory.sadd(self.dynamic_part)
              return result
docs: If a command is called for the main field, without dynamic part, an
          ImplementationError is raised: commands can only be applied on dynamic
          versions.
          On dynamic versions, if the command is a modifier, we add the version in
          the inventory.