sec -trees /*add new key/value pair to the node there might be subtree associated with the record being added this information comes in the form of - tree node with one key and (possibly nullsubtree through the center pointer field *public ttnode add(ttnode itif (rkey =null/only one keyadd here if (lkey compareto(it lkey() rkey it lkey()rval it lval()right centercenter it cchild()else rkey lkeyrval lvalright centerlkey it lkey()lval it lval()center it cchild()return thiselse if (lkey compareto(it lkey()> /add left center new ttnode(rkeyrvalnullnullcenterrightnull)rkey nullrval nullright nullit setleftchild(left)left itreturn thiselse if (rkey compareto(it lkey() /add center it setcenterchild(new ttnode(rkeyrvalnullnullit cchild()rightnull))it setleftchild(this)rkey nullrval nullright nullreturn itelse /add right ttnode new ttnode(rkeyrvalnullnullthisitnull)it setleftchild(right)right nullrkey nullrval nullreturn figure the - tree node add method