begin
var a := 2;
var b := 3;
var c := 4;
var s := $'Hello {a}';
assert(s = 'Hello 2');
s := $'{a},{b},{c}';
assert(s = '2,3,4');
s := $'{a+1},{b+1},{c+1}';
assert(s = '3,4,5');
assert($'abc'=$'abc');
end.