code: private static Node fuseIntoOneStatement(Node parent, Node first, Node last) {
      // Nothing to fuse if there is only one statement.
      if (first.getNext() == last) {
        return first;
      }
  
      // Step one: Create a comma tree that contains all the statements.
      Node commaTree = first.removeFirstChild();
  
      Node next = null;
      for (Node cur = first.getNext(); cur != last; cur = next) {
        commaTree = fuseExpressionIntoExpression(
            commaTree, cur.removeFirstChild());
        next = cur.getNext();
        parent.removeChild(cur);
      }
  
      // Step two: The last EXPR_RESULT will now hold the comma tree with all
      // the fused statements.
      first.addChildToBack(commaTree);
      return first;
    }
docs: Given a block, fuse a list of statements with comma's.
  
  @param parent The parent that contains the statements.
  @param first The first statement to fuse (inclusive)
  @param last The last statement to fuse (exclusive)
  @return A single statement that contains all the fused statement as one.