anchor.diff:          else power_num num_10 (Int n)
   
   /// Returns numerator and denominator of normalized fraction.
  -let numdom r = 
  +let numdom r =
       let r' = Ratio.normalize_ratio(ratio_of_num r)
       num_of_big_int(Ratio.numerator_ratio r'), num_of_big_int(Ratio.denominator_ratio r')
   
  
positive.code: (* ------------------------------------------------------------------------- *)
  
  /// Concatenates a list of strings into one string.
  // OPTIMIZE : Make this an alias for List.sortWith.
  let implode l = itlist (+) l ""
  
  /// Converts a string into a list of single-character strings.
  
negative.code: (* ------------------------------------------------------------------------- *)
  
  /// Tests if an element is equivalent to a member of a list w.r.t. some relation.
  let rec mem' eq =
      let rec mem x lis = 
          match lis with
          | [] -> false
  