docs: def to_dict(self, converter=None):
          """Returns a copy dict of the current object
  
          If a converter function is given, pass each value to it.
          Per default the values are converted by `self.stringify`.
          """
          if converter is None:
              converter = self.stringify
          out = dict()
          for k, v in self.iteritems():
              out[k] = converter(v)
          return out