isFlipEquiv that takes two nodes, node1 and node2, as arguments.node1 and node2 are null, return true.node1 or node2 is null, or if their values are not equal, return false.node1.left with node2.left and node1.right with node2.right, or node1.left with node2.right and node1.right with node2.left.true if either of the recursive checks returns true.