Two trees, T$1$ and T$2,$ are isomorphic if T$1$ can be transformed

into T$2$ by swapping left and right children of $($some of the$)$ nodes in T$1.$ For instance, the

two trees in the following figure are isomorphic because they are the same if the children

of A$,$ B$,$ and G$,$ but not the other nodes, are swapped