code: @Override
    protected boolean hasOverflow(N node) {
      if(node.isLeaf()) {
        return node.getNumEntries() == leafCapacity;
      }
      else {
        return node.getNumEntries() == dirCapacity;
      }
    }
docs: Returns true if in the specified node an overflow occurred, false
  otherwise.
  
  @param node the node to be tested for overflow
  @return true if in the specified node an overflow occurred, false otherwise