use aiken/builtin fn concat(left: String, right: String) -> String { builtin.append_bytearray( builtin.encode_utf8(left), builtin.encode_utf8(right), ) |> builtin.decode_utf8 } fn is_negative(i: Int) -> Bool { if i < 0 { trace @"is negative" True } else { trace concat(@"is", concat(@" ", @"non-negative")) False } } test trace_1() { is_negative(-14) && !is_negative(42) }