docs: def get_marshaller_for_type_string(self, type_string):
          """ Gets the appropriate marshaller for a type string.
  
          Retrieves the marshaller, if any, that can be used to read/write
          a Python object with the given type string. The modules it
          requires, if available, will be loaded.
  
          Parameters
          ----------
          type_string : str
              Type string for a Python object.
  
          Returns
          -------
          marshaller : marshaller or None
              The marshaller that can read/write the type to
              file. ``None`` if no appropriate marshaller is found.
          has_required_modules : bool
              Whether the required modules for reading the type are
              present or not.
  
          See Also
          --------
          hdf5storage.Marshallers.TypeMarshaller.python_type_strings
  
          """
          if type_string in self._type_strings:
              index = self._type_strings[type_string]
              m = self._marshallers[index]
              if self._imported_required_modules[index]:
                  return m, True
              if not self._has_required_modules[index]:
                  return m, False
              success = self._import_marshaller_modules(m)
              self._has_required_modules[index] = success
              self._imported_required_modules[index] = success
              return m, success
          else:
              return None, False