def valid_date(x: str) -> bool:
    """
    Retrun ``True`` if ``x`` is a valid YYYYMMDD date;
    otherwise return ``False``.
    """
    try:
        if x != dt.datetime.strptime(x, DATE_FORMAT).strftime(DATE_FORMAT):
            raise ValueError
        return True
    except ValueError:
        return False
def valid_date ( x : str ) -> bool : try : if x != dt . datetime . strptime ( x , DATE_FORMAT ) . strftime ( DATE_FORMAT ) : raise ValueError return True except ValueError : return False
Retrun ``True`` if ``x`` is a valid YYYYMMDD date;
    otherwise return ``False``.