code: public void setEmpty()
      {
          this.value = "";
          this.leading = this.trailing = 0;
          this.isEmpty = true;
          if (this.previous != null)
          {
              this.previous.nextEmpty = true;
          }
          if (this.next != null)
          {
              this.next.prevEmpty = true;
          }
      }
docs: Marks this line empty. Also sets previous/next line's empty attributes.