def chained_get(self, *keys):
existing = self<EOL>for i in range(<NUM_LIT:0>, len(keys)):<EOL><INDENT>if keys[i] in existing:<EOL><INDENT>existing = existing[keys[i]]<EOL><DEDENT>else:<EOL><INDENT>return None<EOL><DEDENT><DEDENT>return existing<EOL>
This function allows traversals over several keys to
be performed by passing a list of keys::

    d.chained_get(key1,key2,key3) = d[key1][key2][key3]