Append a new pathspec component to this pathspec.

def Append(self, component=None, **kwarg):
    """Append a new pathspec component to this pathspec."""
    if component is None:
      component = self.__class__(**kwarg)

    if self.HasField("pathtype"):
      self.last.nested_path = component
    else:
      for k, v in iteritems(kwarg):
        setattr(self, k, v)

      self.SetRawData(component.GetRawData())

    return self