Merge dictionaries.
Merge many dicts, handling specific scenarios where a key exists in both
dictionaries but has a value of None in 'left'. In such cases, the method uses
the value from 'right' for that key in the merged dictionary.
Example:
If left = {"function_call": {"arguments": None}} and
right = {"function_call": {"arguments": "{\n"}}, then, after merging, for the
key 'function_call', the value from 'right' is used, resulting in
merged = {"function_call": {"arguments": "{\n"}}.
