require.py 文件源码

def require_list(value: Optional[List[Any]], item_type: Any=None, allow_none: bool=False) -> Any:
    """Make sure a value is a List[item_type].

    Used when dealing with http input data.
    """
    if value is None and allow_none:
        return value
    if type(value) != list:
        raise InvalidData('value was %s, expected list' % type(value))
    value = cast(List, value)
    if item_type:
        for item in value:
            if type(item) != item_type:
                raise InvalidData('list item was %s, expected %s' % (type(item), item_type))
    return value