modifier (Color fg bg) = \x -> concat ["<fc=", fg, if null bg then "" else "," ++ bg
                                      , ">", x, "</fc>"]
modifier (Color fg bg) = \x -> concat ["<fc=", fg, if null bg then "" else "," ++ bg
                                      , ">", x, "</fc>"]
modifier (Color fg bg) = \x -> concat ["<fc=", fg, if null bg then "" else "," ++ bg
                                      , ">", x, "</fc>"]