code: def add_marshaller(self, marshallers):
          
          if not isinstance(marshallers, collections.Iterable):
              marshallers = [marshallers]
          for m in marshallers:
              if not isinstance(m, Marshallers.TypeMarshaller):
                  raise TypeError('Each marshaller must inherit from '
                                  'hdf5storage.Marshallers.'
                                  'TypeMarshaller.')
              if m not in self._user_marshallers:
                  self._user_marshallers.append(m)
          self._update_marshallers()
docs: Add a marshaller/s to the user provided list.
  
          Adds a marshaller or a list of them to the user provided set of
          marshallers.
  
          Note that the builtin marshallers take priority when choosing
          the right marshaller.
  
          .. versionchanged:: 0.2
             All marshallers must now inherit from
             ``hdf5storage.Marshallers.TypeMarshaller``.
  
          .. versionchanged:: 0.2
             Builtin marshallers take priority over user provided ones.
  
          Parameters
          ----------
          marshallers : marshaller or iterable of marshallers
              The user marshaller/s to add to the user provided
              collection. Must inherit from
              ``hdf5storage.Marshallers.TypeMarshaller``.
  
          Raises
          ------
          TypeError
              If one of `marshallers` is the wrong type.
  
          See Also
          --------
          hdf5storage.Marshallers.TypeMarshaller