code: public String diff_text1(LinkedList<Diff> diffs) {
          StringBuilder text = new StringBuilder();
          for (Diff aDiff : diffs) {
              if (aDiff.operation != Operation.INSERT) {
                  text.append(aDiff.text);
              }
          }
          return text.toString();
      }
docs: Compute and return the source text (all equalities and deletions).
  
  @param diffs
  LinkedList of Diff objects.
  @return Source text.