def METHOD_NAME():
    # 2. test dict update with values as dictionaries themselves
    a1 = dict(a=1, b="hello", c=23)
    b1 = dict(a=3, b="goodbye", d="compare")
    a2 = dict(a=1, c=a1)
    b2 = dict(a=3, b="compare", c=b1)
    result2 = dict_deep_update(a2, b2)
    correct_result = dict(a=3, b="compare", c=dict_deep_update(a1, b1))
    compare_dicts(result2, correct_result)