code: public final boolean setChildAt(BinaryTreeZone zone, N newChild) {
  		switch (zone) {
  		case LEFT:
  			return setLeftChild(newChild);
  		case RIGHT:
  			return setRightChild(newChild);
  		default:
  			throw new IndexOutOfBoundsException();
  		}
  	}
docs: Set the child for the specified zone.
  
  @param zone is the zone to set
  @param newChild is the child to insert
  @return <code>true</code> if the child was added, otherwise <code>false</code>