#lang bracket

DeclareVars(x,y);

{2}+x;
x+{3};
x+{4,5};
{4,5}+x;
{3,4}+{x,y};
{3,4,5}+{x,y};
{6}*x;
x*{7};
x*{8,9};
{10,11}*{x,y}