nodes.py 文件源码

def __getitem__(self, key):
        if isinstance(key, basestring):
            return self.attributes[key]
        elif isinstance(key, int):
            return self.children[key]
        elif isinstance(key, types.SliceType):
            assert key.step in (None, 1), 'cannot handle slice with stride'
            return self.children[key.start:key.stop]
        else:
            raise TypeError, ('element index must be an integer, a slice, or '
                              'an attribute name string')