1. In the next levels of the heap, all the nodes have the same number of descendants.
2. In the middle levels (layers), there are no nodes without children.
3. The only level that may have an incomplete structure of the descendants is
second to last. Having children in this level depends on the number of items
in the string that we are deploying in the created heap.
4. In the level, elements are placed in the nodes from the left to the right side
of the heap.
Andrzej