anchor.diff:  
    * +preserve_indent+: insert previous line indent when inserting a newline
    * +cleanup_whitespaces+: remove trailing whitespaces on the previous line
  -                          when inserting an end-of-line.
  +       when inserting an end-of-line.
    * +expand_tabulations+: insert spaces instead of tab characters
  - * +regex+: takes three arguments: current line regex, inserted text regex
  -      and replacement text. when the current line regex and inserted text
  -      regex matches, replace insereted text with the replacement text.
  -      capture groups are available through $[0-9] escape sequence, and
  -      cursor position can be specified with $c.
  + * +regex <line_regex> <insert_regex> <replacement>+: when the current line regex
  +       and inserted text regex matches, replace insereted text with the
  +       replacement text. Capture groups are available through $[0-9] escape
  +       sequence, and cursor position can be specified with $c.
    * +group+: same as highlighters group
   
   Hooks
  
positive.code: 
  existing highlighters are:
  
   * +highlight_selections+: used to make current selection visible
   * +expand_tabs+: expand tabs to next 8 multiple column (to make configurable)
   * +number_lines+: show line numbers
   * +group+: highlighter group, containing other highlighters. takes one
              parameter, <group_name>. useful when multiple highlighters work
              together and need to be removed as one. Adding and removing from
              a group can be done using
              `:addhl -group <group> <highlighter_name> <highlighter_parameters...>`
              `:rmhl  -group <group> <highlighter_name>`
   * +regex+: highlight a regex, takes the regex as first parameter, followed by
              any number of color spec parameters.
              color spec format is: <capture_id>:<fg_color>[,<bg_color>]
              For example: `:addhl regex //(\h+TODO:)?[^\n]+ 0:cyan 1:yellow,red`
              will highlight C++ style comments in cyan, with an eventual
              'TODO:' in yellow on red background.
  
  Filters
  -------
  
negative.code:  * +eval [-client <name>] <command>+: execute <command> as if entered in command line
        if client if specified, exec command in the named client context.
   * +echo <text>+: show <text> in status line
   * +decl <type> <name> [<value>]+:  declare an option, type can be int, str, int-list
        and str-list.
   * +set{b,w,g} <option> <value>+: set <option> to <value> in *b*uffer, *w*indow
        or *g*lobal scope.
   * +name <name>+: sets current client name to name
   * +c[ol]a[lias] <name> <colspec>+: define a color alias, so that name can be
        used instead of colspec in contexts where a color is needed.
   * +nop+: does nothing, but as with every other commands, arguments may be
  