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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 _deep_merge_dict(a, b):
 """Additively merge right side dict into left side dict."""

    for k, v in b.items():
        if k in a and isinstance(a[k], dict) and isinstance(v, dict):
            _deep_merge_dict(a[k], v)
        else:
            a[k] = v