'Logs a message with pre-formatted prefix.
:param int level:
Logging level as specified in the
`login module <http://docs.python.org/2/library/logging.html>`_ of
Python standard library.
:param str msg:
The actual message.'

@classmethod
def _log(cls, level, msg, **kwargs):

    logger = (getattr(cls, '_logger', None) or authomatic.core._logger)
    logger.log(level, ':    '.join(('authomatic', cls.__name__, msg)), **kwargs)
