Add ability to insert last leaf to the tree

[3q-coder]

It looks like it is necessary to replace MAX_LEAF_COUNT - 1 with MAX_LEAF_COUNT. Because it is impossible to insert the last leaf in the current implementation.

[HarryR]

You are correct, thank you for spotting that :D

For example, MAX_LEAF_COUNT = 4

You try to insert 4 times, incrementing self._cur which starts at zero, which represents the index of the next leaf which will be inserted.

• _cur=0
• _cur=1
• _cur=2
• _cur=3 <--- it will fail here, because _cur == 3

So last item will fail to insert.