def _deep_merge_dict(a, b):
for k, v in b.items():<EOL><INDENT>if k in a and isinstance(a[k], dict) and isinstance(v, dict):<EOL><INDENT>_deep_merge_dict(a[k], v)<EOL><DEDENT>else:<EOL><INDENT>a[k] = v<EOL><DEDENT><DEDENT>
Additively merge right side dict into left side dict.