def substitute(self, substitutions):
        for (var,cat) in substitutions:
            if var == self:
                 return cat
        return self
Async version of cas_multi() -- note different return value.
dataset/ETHPy150Open nltk/nltk/nltk/ccg/api.py/CCGVar.substitute--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/api/memcache/__init__.py/Client.cas_multi_async