Implementation of ADT Tree (array) to perform the following operations on an ordered general tree
a. create a tree (which is initially empty) ... max of 2 levels only
b. leftmost child (n, T) - returns the leftmost node in the tree T
c. right_sibling(n,T) - returns the right sibling of a node.
d. parent (n,T) - returns the parent of node n in the tree T.
e. root(T) - returns the root node of a tree