def format_period(period):
    """Build a pretty name for a time interval.

    Parameters
    ----------
    period: pandas.Interval, required
        The time interval to format.

    Returns
    -------
    name: str
        The period name in format '<period.left>-<period.right>'.
    """
    left, right = int(period.left), int(period.right)
    return '{left}-{right}'.format(left=left, right=right)