def _parse_periods(pattern):
    parts = pattern.split('..', 1)
    if len(parts) == 1:
        instant = Period.parse(parts[0])
        return (instant, instant)
    else:
        start = Period.parse(parts[0])
        end = Period.parse(parts[1])
        return (start, end)
Parse a string containing two dates separated by two dots (..).
dataset/ETHPy150Open beetbox/beets/beets/dbcore/query.py/_parse_periods