Function parentIndex(index){
  return (index - 1) / 2
End Function



Function leftChildIndex(index){
  return (index * 2) + 1
End Function


Function bubbleUp(index)
  parent_index = parentIndex(index)
  While (priority at parent_index < priority at index)
        and (index > 0):
    swap items at index and parent index
    index = parent_index
    parent_index = parentIndex(index)
  End While
End Function