How to use the reil.arm.operand.set function in reil

def _arm_mov(ctx, i):
    prev_value = operand.get(ctx, i, 1)
    value = ctx.tmp(ctx.word_size)

    ctx.emit(  str_  (prev_value, value))

    if i.update_flags:
        set_N(ctx, value)
        set_Z(ctx, value)

    operand.set(ctx, i, 0, value)

ctx.emit(  and_  (prev_value, imm(mask(16), 32), value))

    # then compute the high 16 bits
    prev_result = operand.get(ctx, i, 1)
    result = ctx.tmp(ctx.word_size)

    ctx.emit(  str_  (prev_result, result))
    ctx.emit(  lshl_ (result, imm(16, 32), result))

    ctx.emit(  or_   (value, result, result))

    if i.update_flags:
        set_N(ctx, result)
        set_Z(ctx, result)

    operand.set(ctx, i, 0, result)

def arm_str(ctx, i):
    value = operand.get(ctx, i, 1)
    operand.set(ctx, i, 0, value)