def __getitem__(self, item):

        if not self.attr_map:
            return self.default
        elif self._ensure_tuple(item) not in self.attr_map.keys():

            # make sure we have attr map
            self.setup()

        return self.attr_map[self._ensure_tuple(item)]
Lookup the attribute to use for the given unique group label.
dataset/ETHPy150Open bokeh/bokeh/bokeh/charts/attributes.py/AttrSpec.__getitem__