Data Structures and Algorithms
with Object-Oriented Design Patterns in Java 
Program 
defines a constructor that
takes a single int argument M
and creates an empty B-tree of order M.
By default, the parent field is null.
The attachSubtree method is used to attach
a new subtree to a given node.
The attachSubtree routine takes an integer, i,
and an M-way tree (which must be a B-tree instance),
and makes it the 
subtree of the given node.
Notice that this method also modifies the parent field
in the attached node.
Copyright © 1998 by Bruno R. Preiss, P.Eng. All rights reserved.