returns the xsi:type as a tuple, coupled with ZSI.schema

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)