what are the valid colors for mercurial's color extension?
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Mercurial's `color` extension (http://mercurial.selenic.com/wiki/ColorExtension) is great and all, but there isn't a list on that page of what the valid colors are. I looked for a python file named color, hoping I'd be able to read the source and see it there, but no luck. I was hoping to use grey or light grey for a color but it wasn't valid. Grey (or gray) seems like a pretty likely color to be in a list of colors. 

Where can I find a list of valid colors for the `color` extension? Or where can I find the source for the `color` extension? 