def parse_date(value):
    if value:
        t = parsedate_tz(value.strip())
        if t is not None:
            try:
                year = t[0]
                # unfortunately that function does not tell us if two digit
                # years were part of the string, or if they were prefixed
                # with two zeroes.  So what we do is to assume that 69-99
                # refer to 1900, and everything below to 2000
                if year >= 0 and year <= 68:
                    year += 2000
                elif year >= 69 and year <= 99:
                    year += 1900
                return datetime(*((year,) + t[1:7])) - \
                       timedelta(seconds=t[-1] or 0)
            except (ValueError, OverflowError):
                return None
Check if the value is valid.
dataset/ETHPy150Open Eforcers/gae-flask-todo/lib/werkzeug/http.py/parse_date--crossover with--dataset/ETHPy150Open sdispater/cleo/cleo/validators/__init__.py/Validator.is_valid