__init__.py 文件源码

def __getitem__(self, key):
        keyname, key, constants = _normalize_arg(key, self._constants)
        return __class__(
            '%s[%s]' % (self._pname, keyname),
            ast.Subscript(
                value=self._tree,
                slice=ast.Index(value=key),
                ctx=ast.Load(),
            ),
            constants,
        )