docs: def push_log(self, info, level=None, *args, **kwargs):
          """
          Prints the log as usual for fabric output, enhanced with the prefix "docker".
  
          :param info: Log output.
          :type info: unicode
          :param level: Logging level. Has no effect here.
          :type level: int
          """
          if args:
              msg = info % args
          else:
              msg = info
          try:
              puts('docker: {0}'.format(msg))
          except UnicodeDecodeError:
              puts('docker: -- non-printable output --')