'Add parse action to expression\'s list of parse actions. See L{I{setParseAction}<setParseAction>}.'

def addParseAction(self, *fns, **kwargs):

    self.parseAction += list(map(_trim_arity, list(fns)))
    self.callDuringTry = (self.callDuringTry or kwargs.get('callDuringTry', False))
    return self
