Re-order a list in level-order (breadth-first traversal), in SuperCollider, using recursion

level_order_sort.scd

(
f = { | list |
	if (list.size == 0) {
		[]
	}{
		list.collect({ | x | (if (x.size > 0) { x[0] } { x })})
		++ f.(list.select ({| x |  x.size > 0}).collect ({|x| x [1..]})
			.select ({|x| x.size > 0}));
	  }
}
)
//: Tests: 
f.([[1], [5], 3]);

// ================================================================
//:
f.([[1, 2], [5, 6, 7], 3]);