code: public void addChildren( AstNode first,
                               AstNode second,
                               AstNode third ) {
          if (first != null) {
              this.addLastChild(first);
          }
          if (second != null) {
              this.addLastChild(second);
          }
          if (third != null) {
              this.addLastChild(third);
          }
      }
docs: Add the supplied nodes at the end of the list of children.
  
  @param first the first child to add
  @param second the second child to add
  @param third the third child to add