375     def _call(self, cmd, **args):

   376         """execute <cmd> on the server

   377 

   378         The command is expected to return a simple string.

   379 

   380         returns the server reply as a string."""

   381         raise NotImplementedError()

   382 

   383     def _callstream(self, cmd, **args):

   384         """execute <cmd> on the server

   385 

   386         The command is expected to return a stream.

   387 

   388         returns the server reply as a file like object."""

   389         raise NotImplementedError()

   390 

   391     def _callpush(self, cmd, fp, **args):

   392         """execute a <cmd> on server

   393 

   394         The command is expected to be related to a push. Push has a special

   395         return method.

   396 

   397         returns the server reply as a (ret, output) tuple. ret is either

   398         empty (error) or a stringified int.

   399         """

   400         raise NotImplementedError()

   401 

   402     def _abort(self, exception):

   403         """clearly abort the wire protocol connection and raise the exception

   404         """

   405         raise NotImplementedError()

   406 

   407 

   408     def _decompress(self, stream):

   409         """decompress a received stream

   410         """

   411         raise NotImplementedError()

   412