'Create a connection to the server.
This method is abstract - concrete implementations should
implement their own variant which connects to the server and
returns an initialized Protocol object with the service ready
for use and a can_read function which may be used to see if
reads would block.
:param cmd: The git service name to which we should connect.
:param path: The path we should pass to the service. (as bytestirng)'

def _connect(self, cmd, path):

    raise NotImplementedError()
