Declare a static variable in an enum class

I have an enum for colors. I wish to add a helper method "toRGB()" to the enum class that converts an instance of the enum to an RGB object. As an optimization, I wished to create the dictionary once as a static variable. However, the correct syntax seems to elude me.

Can anyone suggest the right way to do this?

from enum import Enum

class RGB:
    def __init__(self, r, g, b):
        pass

class Color(Enum):
    RED = 0
    GREEN = 1

    __tbl = {
              RED:   RGB(1, 0, 0),
              GREEN: RGB(0, 1, 0)
            }

    def toRGB(self):
        return self.__class__.__tbl[self.value]

c = Color.RED
print(c.toRGB())

I get the following error:

Traceback (most recent call last):
  File "C:/Users/user/Desktop/test.py", line 20, in <module>
    print(c.toRGB())
  File "C:/Users/user/Desktop/test.py", line 17, in toRGB
    return self.__class__.__tbl[self.value]
TypeError: 'Color' object does not support indexing

Non-method attributes become enum members (even tbl). You can use a keyword argument instead:

class Color(Enum):
    RED = 0
    GREEN = 1

    def toRGB(self, tbl={
        RED:   RGB(1, 0, 0),
        GREEN: RGB(0, 1, 0)
    }):
        return tbl[self.value]

Alternatively, you can define the attribute after class creation:

class Color(Enum):
    RED = 0
    GREEN = 1

    def toRGB(self):
        return self._tbl[self]

Color._tbl = {
    Color.RED:   RGB(1, 0, 0),
    Color.GREEN: RGB(0, 1, 0)
}