{x | x in {1,2,3}}
{x | x in {1,2,3}, y in {}}
{x+y+z | z in {1,2,3}, x in {z-1,z+1}, y in {10,20,30}}
{x+y+z | x in {1,2}, y in {1,2}, z in {1,2}}
{ x | x in {1,2,3}, x > 1 }