code: function diff_cleanupSemanticScore_(one, two) {
      if (!one || !two) {
        // Edges are the best.
        return 5;
      }
  
      // Each port of this function behaves slightly differently due to
      // subtle differences in each language's definition of things like
      // 'whitespace'.  Since this function's purpose is largely cosmetic,
      // the choice has been made to use each language's native features
      // rather than force total conformity.
      var score = 0;
      // One point for non-alphanumeric.
      if (one.charAt(one.length - 1).match(punctuation) ||
          two.charAt(0).match(punctuation)) {
        score++;
        // Two points for whitespace.
        if (one.charAt(one.length - 1).match(whitespace) ||
            two.charAt(0).match(whitespace)) {
          score++;
          // Three points for line breaks.
          if (one.charAt(one.length - 1).match(linebreak) ||
              two.charAt(0).match(linebreak)) {
            score++;
            // Four points for blank lines.
            if (one.match(blanklineEnd) || two.match(blanklineStart)) {
              score++;
            }
          }
        }
      }
      return score;
    }
docs: Given two strings, compute a score representing whether the internal
  boundary falls on logical boundaries.
  Scores range from 5 (best) to 0 (worst).
  Closure, makes reference to regex patterns defined above.
  @param {string} one First string.
  @param {string} two Second string.
  @return {number} The score.
  @private