'Read in the list of indexed colors'

def parse_color_index(self):

    colors = self.root.findall(('{%s}colors/{%s}indexedColors/{%s}rgbColor' % (SHEET_MAIN_NS, SHEET_MAIN_NS, SHEET_MAIN_NS)))
    if (not colors):
        return
    self.color_index = IndexedList([node.get('rgb') for node in colors])
