anchor.diff:            };
   
             style = mkOption {
  -            type = types.str // {
  -              check = flip elem ["none" "slight" "medium" "full"];
  -            };
  +            type = types.enum ["none" "slight" "medium" "full"];
               default = "full";
               description = ''
                 TrueType hinting style, one of <literal>none</literal>,
  
positive.code:             default = "default";
              type = types.enum ["none" "default" "light" "legacy"];
              description = ''
                FreeType LCD filter, one of <literal>none</literal>,
                <literal>default</literal>, <literal>light</literal>, or
                <literal>legacy</literal>.
              '';
            };
  
  
negative.code:             default = "rgb";
              type = types.enum ["rgb" "bgr" "vrgb" "vbgr" "none"];
              description = ''
                Subpixel order.
              '';
            };
  
  