let program =
#|add a0, a0, a1
#|sub a3, a0, a2
// ...
let assembler = Assembler::new(32, ["g", "c"]);
// Gives one UInt for a single instruction.
let insts: Array[UInt] = assembler.assemble(program);
// Gives a byte stream for the code.
let bytes: Bytes = assembler.assemble_bytes(program);