def is_color(self, color):
return not (color is None or hasattr(color, "<STR_LIT>"))<EOL>
Tests to see if a color is defined.
Because colors can be set to None in the config and we want this to be
respected in an expression like.

color = self.py3.COLOR_MUTED or self.py3.COLOR_BAD

The color is treated as True but sometimes we want to know if the color
has a value set in which case the color should count as False.  This
function is a helper for this second case.