(seq)
return res
Internal function.
Internal function.
Internal function .
def _flatten(seq):
    """Internal function."""
    res = ()
    for item in seq:
        if isinstance(item, (tuple, list)):
            res = res + _flatten(item)
        elif item is not None:
            res = res + (item,)
    return res
def _flatten ( seq ) : res = ( ) for item in seq : if isinstance ( item , ( tuple , list ) ) : res = res + _flatten ( item ) elif item is not None : res = res + ( item , ) return res