anchor.diff:      interpreted as a *display line* to display in place of the range.
       Here, the 3 first chars of the buffer will be replaced by the word 'red':
   
  --------------------------------------------------
  +--------------------------------------------------------
   declare-option range-specs my_range
  -set-option window my_range 1486635122:1.1,1.3|red
  +set-option window my_range "%val{timestamp}:1.1,1.3|red"
   add-highlighter window/ replace-ranges my_range
  --------------------------------------------------
  +--------------------------------------------------------
   
   == Highlighting Groups
   
  
positive.code:     In this example two words will be added in the gutter: a blue Foo at
      line 1 and a bold red/yellow Bar on line 3:
  
  ---------------------------------------------------------------
  declare-option line-specs my_flags
  set-option window my_flags 1486635122:1|Foo:3|{red,yellow+b}Bar
  add-highlighter window/ flag_lines blue my_flags
  ---------------------------------------------------------------
  
  *ranges* <option_name>::
      use the data in the `range-specs` option of the given name to highlight
  
negative.code:     interpreted as a *face* to apply to the range.
      In this example the 3 first chars of the buffer will be colored in red:
  
  --------------------------------------------------------
  declare-option range-specs my_range
  set-option window my_range "%val{timestamp}:1.1,1.3|red"
  add-highlighter window/ ranges my_range
  --------------------------------------------------------
  
  *replace-ranges* <option_name>::
      use the data in the `range-specs` option of the given name to highlight
  