ATTR_ACCESS:
Testing with 1000000 repeats:

    >>> OldEnum['foo']  # 0.663708519 seconds
    <OldEnum.foo: 1>

    >>> NewEnum['foo']  # 0.32571259499999994 seconds
    <NewEnum.foo: 1>

    >>> OldEnum.foo  # 0.16809049799999998 seconds
    <OldEnum.foo: 1>

    >>> NewEnum.foo  # 0.06393614900000011 seconds
    <NewEnum.foo: 1>

    >>> OldEnum.foo.value  # 0.6732232629999999 seconds
    1

    >>> NewEnum.foo.value  # 0.1533165799999998 seconds
    1

    >>> OldEnum.value.value  # 1.9447311319999998 seconds
    3

    >>> NewEnum.value.value  # 0.1025070509999999 seconds
    3

    >>> try:     OldEnum.value.value = 'new' except: pass  # 2.048566492 seconds
    AttributeError("can't set attribute")

    >>> try:     NewEnum.value.value = 'new' except: pass  # 0.596396082 seconds
    AttributeError("Can't set attribute")

NewEnum: total: 1.2418685, average: 0.1811723 (Fastest)
OldEnum: total: 5.4983199, average: 0.7855935, ~ x4.34 times slower than NewEnum