A free tree is never rooted,
Infinite complete binary tree.
A finger tree has internal nodes and
Each one in this tree has child nodes.
And their connection is a walk,
Parents and children walking the tree.
Nodes without children are called leaves,
While roots are leaves for the finger trees.
Very intelligent are the words tree,
Trees-no one-to-one correspondence,
Adaptive merging operation,
Implementing finger search trees.