def enablePackrat():
        if not ParserElement._packratEnabled:
            ParserElement._packratEnabled = True
            ParserElement._parse = ParserElement._parseCache
Enables "packrat" parsing, which adds memoizing to the parsing logic.
dataset/ETHPy150Open ipython/ipython-py3k/IPython/external/pyparsing/_pyparsing.py/ParserElement.enablePackrat