private void optst(Subre t) {
        if (t == null) {
            return;
        }

    /* recurse through children */
        if (t.left != null) {
            optst(t.left);
        }
        if (t.right != null) {
            optst(t.right);
        }
    }
private void optst(Subre t) {
        if (t == null) {
            return;
        }

    
        if (t.left != null) {
            optst(t.left);
        }
        if (t.right != null) {
            optst(t.right);
        }
    }
private void optst ( Subre t ) { if ( t == null ) { return ; } /* recurse through children */ if ( t . left != null ) { optst ( t . left ) ; } if ( t . right != null ) { optst ( t . right ) ; } }
optst - optimize a subRE subtree
optst - optimize a subRE subtree