167 def _divertopener(opener, target):

   167 class _divertopener(object):

   168     """build an opener that writes in 'target.a' instead of 'target'"""

   168     def __init__(self, opener, target):

   169 

   169         self._opener = opener

   170     def _divert(name, mode=b'r', checkambig=False, **kwargs):

   170         self._target = target

   171         if name != target:

   171 

   172             return opener(name, mode, **kwargs)

   172     def __call__(self, name, mode=b'r', checkambig=False, **kwargs):

   173         return opener(name + b".a", mode, **kwargs)

   173         if name != self._target:

   174 

   174             return self._opener(name, mode, **kwargs)

   175     return _divert

   175         return self._opener(name + b".a", mode, **kwargs)

   176 

   177     def __getattr__(self, attr):

   178         return getattr(self._opener, attr)