flatten:1, 2, 3, 4, 5, 6, 7, 8, 9, 10, a, b, c, 28, 42, 84, foo bar
lr_flatten:1, 2, 3, 4, 5, 6, 7, 8, 9, 10, a, b, c, foo bar, 28, 42, 84
*  flatten:bar, baz, 2, foo, 1, baz, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, a, b, c, 28, 42, 84, foo bar