import logging


def timestamp_formatter() -> logging.Formatter:
    """Returns a logging formatter which outputs in the style of
    ``YEAR-MONTH-DAY HOUR:MINUTE:SECOND.MILLISECOND LEVEL MESSAGE``.
    """
    return logging.Formatter(
        fmt="%(asctime)s.%(msecs)03d %(levelname)-8s %(message)s",
        datefmt="%Y-%m-%d %H:%M:%S",
    )