code: public int diff_levenshtein(LinkedList<Diff> diffs) {
          int levenshtein = 0;
          int insertions = 0;
          int deletions = 0;
          for (Diff aDiff : diffs) {
              switch (aDiff.operation) {
              case INSERT:
                  insertions += aDiff.text.length();
                  break;
              case DELETE:
                  deletions += aDiff.text.length();
                  break;
              case EQUAL:
                  // A deletion and an insertion is one substitution.
                  levenshtein += Math.max(insertions, deletions);
                  insertions = 0;
                  deletions = 0;
                  break;
              }
          }
          levenshtein += Math.max(insertions, deletions);
          return levenshtein;
      }
docs: Compute the Levenshtein distance; the number of inserted, deleted or
  substituted characters.
  
  @param diffs
  LinkedList of Diff objects.
  @return Number of changes.