anchor.diff:     "If object length is bigger than `len', cut the last characters out.
   
   Also replaces the last n characters (where n is the length of
  -`truncate-string') of the shortened string with `truncate-string'. 
  +`truncate-string') of the shortened string with `truncate-string'.
   
   It defaults to ..., but can be nil or the empty string."))
   
  
positive.code: 
  (defgeneric text-slice (object start &optional end)
    (:documentation
     "Returns a sub-sequence of `object' starting from `start` and terminating at `end'. 
  
  If end in nil the the sub sequence ends alt the last element of the sequence."))
  
  
negative.code: 
  (defgeneric concat-complex-string (a b &key color-attributes-contagion)
    (:documentation
     "Return a new `complex-string' that is the result of concatenating `a' and 'b'.
  
  If `color-attributes-contagion' is non nil, `b' will inherit all the
  attributes and color of the last element of `a'."))
  