def validate_datetime(value):
    if isinstance(value, datetime.datetime):
        return value

    for format_ in date_formats:
        try:
            return datetime.datetime.strptime(value, format_)
        except ValueError:
            pass
    raise ValidationError(value % "Invalid date format: %s")
dataset/ETHPy150Open dnephin/PyStaticConfiguration/staticconf/validation.py/validate_datetime/swapped operands of `%`