fc44991 - Replace DICT by PAIRS and do_dict by do_pairs.
67d2f7e - Add flag IGNORE and use in flatten_factory.
0ded745 - Add flag VALUE_DICT and use in flatten_factory (plus minor refactor of DICT case).
1a3cb75 - Add flag VALUE_AS_IS and use it in flatten_factory.
ed536f7 - Add docstring with some tests to flatten_factory.
d39b3d1 - Add Enum class and use it for the flags.
16fffc0 - Add some tests to docstring for decide(node).
9d23ee1 - Make enter sentinel private to flatten.
1eb5763 - Give flatten_factory sensible default values.
c983266 - Move documentation for assemble_factory and flatten_factory to associated instances.