flatten: a: b: 1, c: d: 2 -> a.b: 1, a.c.d: 2 recursive DFS building dotted key path. then unflatten (inverse). split on ., walk into dict creating intermediate dicts. edge case: keys w . in them. they wanted us to discuss this, not solve it perfectly

xAI TPS intern - flatten JSON oct-dec

flatten: {"a": {"b": 1, "c": {"d": 2}}} -> {"a.b": 1, "a.c.d": 2} recursive DFS building dotted key path.