docs: def _get_xsitype(pyclass):
      '''returns the xsi:type as a tuple, coupled with ZSI.schema
      '''
      if hasattr(pyclass,'type') and type(pyclass.type) in _seqtypes:
          return pyclass.type
      elif hasattr(pyclass,'type') and hasattr(pyclass, 'schema'):
          return (pyclass.schema, pyclass.type)
  
      return (None,None)