anchor.diff:      is not a valid regex
   
   *coord*::
  -    a line, column pair (separated by comma)
  +    a line, column pair (separated by a comma)
   
   *<type>-list*::
       a list, elements are separated by a colon (:) if an element needs
  -    to contain a colon, it can be escaped with a backslash
  +    to contain a colon, it can be escaped with a backslash.
  +    `set -add` appends the new element to the list
   
   *range-specs*::
       a `:` separated list of a pair of a buffer range (`<begin
  
positive.code:     updated according to all the buffer modifications that happened
      since its timestamp.
      See <<highlighters#specs-highlighters,`:doc highlighters specs-highlighters`>>)
  
  *line-specs*::
      a `:` separated list of a line number and a corresponding flag
  
negative.code:     an option of this type, its lines gets updated according to all the
      buffer modifications that happened since its timestamp.
      See <<highlighters#specs-highlighters,`:doc highlighters specs-highlighters`>>)
      `set -add` appends the new spec to the list
  
  *completions*::
      a `:` separated list of `<text>|<docstring>|<menu text>`
  