Binary Search Trees
The nodes of a binary tree contain values.
For a binary search tree, it is really sorted
according to the key values in the nodes.
It allows us to traverse a binary tree and get our data in
sorted order!
For example, for each node n, all values greater than n
are located in the right subtree...all values less than n
are located in the left subtree. Both subtrees are
considered to be binary trees themselves.