def enqueue( heap, key, value ):
	"""
	   enqueue: SBBTreeHeap Orderable Any -> NoneType
	   Adds the key/value pair to the heap.
	   Raises TypeError if heap is not an instance of SBBTreeHeap.
	   Must be an O(log n) operation.
	"""

	if ( empty( heap ) ):
		heap = SBBTreeHeap
		heap.root = TreeNode ( key, value, None )
		return heap
	else:
		if ( heap.root.lchild == None and heap.root.rchild == None ):
			heap.root.lchild = TreeNode ( key, value, heap.root )
			heap.root.lchild.parent = heap.root
			heap.root.size += 1
			siftUp ( heap.root.lchild )
			return heap
		if ( heap.root.lchild != None ):
			heap.root.rchild = TreeNode ( key, value, heap.root )
			heap.root.rchild.parent = heap.root
			heap.root.size += 1
			siftUp ( heap.root.rchild )
			return heap
		if ( heap.root.lchild != None and heap.root.rchild != None ):
			if ( heap.root.lchild.size >= heap.root.rchild.size ):
				enqueue( heap.root.rchild, key, value )
				heap.root.size += 1
			else:
				enqueue( heap.root.lchild, key, value )
				heap.root.size += 1
		return heap