# In CPython implementation of Python 3.6, dictionary keeps the insertion order.
# As of Python 3.7, this will become the language feature.
# In order to sort a dictionary including nested dictionary inside, we do:

test_dict = {'a': 1, 'c': 3, 'b': {'b2': 2, 'b1': 1}}

def sort_dict(item):
    if isinstance(item, dict):
        item = {k: v for k, v in sorted(item.items())}
        for k, v in item.items():
            if isinstance(v, dict):
                item[k] = sort_dict(v)
    return item

sorted_dict = sort_dict(test_dict)

print(sorted_dict)
# {'a': 1, 'b': {'b1': 1, 'b2': 2}, 'c': 3}