advanced patterns with Python 3.10's dict merging operator on nested dictionaries
I'm upgrading from an older version and I'm relatively new to this, so bear with me. I've searched everywhere and can't find a clear answer. I'm working with an scenario with the new dictionary merging operator (`|`) introduced in Python 3.9. My expectation is that when I merge two dictionaries containing nested dictionaries, the nested dictionaries should remain intact. However, I’m observing unexpected behavior that isn't documented well. Here’s a minimal example to illustrate the question: ```python # Sample dictionaries nested_dict_a = {'a': 1, 'b': {'c': 2}} nested_dict_b = {'b': {'d': 3}, 'e': 4} # Merging dictionaries merged_dict = nested_dict_a | nested_dict_b print(merged_dict) ``` I expected the output to maintain the nested structure for the key `'b'`, like this: ```python {'a': 1, 'b': {'c': 2}, 'e': 4} ``` But instead, I get: ```python {'a': 1, 'b': {'d': 3}, 'e': 4} ``` It seems that the value for key `'b'` in `nested_dict_b` is overriding the entire value from `nested_dict_a`, instead of merging them. I've read through the [Python documentation](https://docs.python.org/3.10/whatsnew/3.9.html#dictionary-merge-and-update) on this feature but couldn't find anything that addresses nested merges. I also tried using the `update()` method, but it behaves the same way when it comes to nested dictionaries. Is there a way to merge dictionaries in a manner that retains the nested structures? Or is there a specific best practice or design pattern I should be following for such cases? Any insights would be greatly appreciated! My development environment is macOS. Thanks in advance! My development environment is Windows. What's the best practice here?