micropython/tests/extmod/ujson_dumps_ordereddict.py

try:
    import ujson as json
    from ucollections import OrderedDict
except ImportError:
    try:
        import json
        from collections import OrderedDict
    except ImportError:
        print("SKIP")
        raise SystemExit

print(json.dumps(OrderedDict(((1, 2), (3, 4)))))