nltk.parse.SteppingRecursiveDescentParser.backtrack¶

SteppingRecursiveDescentParser.backtrack()[source]¶

Return the parser to its state before the most recent match or expand operation. Calling undo repeatedly return the parser to successively earlier states. If no match or expand operations have been performed, undo will make no changes.

Returns:	true if an operation was successfully undone.
Return type:	bool