def METHOD_NAME(self):
    '''Builds the internal dictionaries from the enum defined in 
    http://cmslxr.fnal.gov/lxr/source/DataFormats/TauReco/interface/PFTau.h'''
    tmp = [
        'kNull',
        'kOneProng0PiZero',
        'kOneProng1PiZero',
        'kOneProng2PiZero',
        'kOneProng3PiZero',
        'kOneProngNPiZero',
        'kTwoProng0PiZero',
        'kTwoProng1PiZero',
        'kTwoProng2PiZero',
        'kTwoProng3PiZero',
        'kTwoProngNPiZero',
        'kThreeProng0PiZero',
        'kThreeProng1PiZero',
        'kThreeProng2PiZero',
        'kThreeProng3PiZero',
        'kThreeProngNPiZero',
        'kRareDecayMode'
        ]
    self.decayModes = dict( (index-1, name) for index, name in enumerate( tmp ) )
    self.decayModeNames = dict( (value, key) for key, value \
                                in self.decayModes.items() )