improvement suggestion for the Coordinate exemple in 3/howto/enum.html about cpython

[fkhn]

oups, wrong copy paste. The proposition was:

class Coordinate(bytes, Enum):
    """
    Coordinate with binary codes that can be indexed by the int code.
    """
    def __new__(cls, value, label, unit):
        obj = bytes.__new__(cls, value)
        obj._value_ = value
        obj.label = label
        obj.unit = unit
        return obj
    PX = (b'0', 'P.X', 'km')
    PY = (b'1', 'P.Y', 'km')
    VX = (b'2', 'V.X', 'km/s')
    VY = (b'3', 'V.Y', 'km/s')