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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def merge_dicts(dict_a, dict_b):
 """Recursively merge dictionary b into dictionary a. If override_nones is True, then """

    def _merge_dicts_(a, b):
        for key in set(a.keys()).union(b.keys()):
            if key in a and key in b:
                if isinstance(a[key], dict) and isinstance(b[key], dict):
                    yield (key, dict(_merge_dicts_(a[key], b[key])))
                elif b[key] is not None:
                    yield (key, b[key])
                else:
                    yield (key, a[key])
            elif key in a:
                yield (key, a[key])
            elif b[key] is not None:
                yield (key, b[key])
    return dict(_merge_dicts_(dict_a, dict_b))