def log_to_stream(stream=sys.stderr, level=logging.NOTSET,
                  fmt=logging.BASIC_FORMAT):
    """ Add :class:`logging.StreamHandler` to logger which logs to a stream.

    :param stream. Stream to log to, default STDERR.
    :param level: Log level, default NOTSET.
    :param fmt: String with log format, default is BASIC_FORMAT.
    """
    fmt = Formatter(fmt)
    handler = StreamHandler()
    handler.setFormatter(fmt)
    handler.setLevel(level)

    log.addHandler(handler)
Add :class:`logging.StreamHandler` to logger which logs to a stream.

    :param stream. Stream to log to, default STDERR.
    :param level: Log level, default NOTSET.
    :param fmt: String with log format, default is BASIC_FORMAT.