assertEvents(
        "R0.00, R1.38, R1.13, R0.88, R0.63, R0.50, R0.50, R0.50", // #1
        "U4.50", // #2
        "R0.00, R1.38, R1.13", // #3, after that the rate changes
        "R0.88", // #4, this is what the throttling would be with the old rate
        "R0.34, R0.28, R0.25, R0.25", // #5
        "U4.25", // #6
        "R0.00, R0.72, R0.66, R0.59, R0.53, R0.47, R0.41", // #7

    assertEvents(
        "R0.00, R1.38, R1.13, R0.88, R0.63, R0.50, R0.50, R0.50", // #1
        "U4.50", // #2
        "R0.00, R1.38, R1.13", // #3, after that the rate changes
        "R0.88", // #4, this is what the throttling would be with the old rate
        "R0.34, R0.28, R0.25, R0.25", // #5
        "U4.25", // #6
        "R0.00, R0.72, R0.66, R0.59, R0.53, R0.47, R0.41", // #7

	goto scan

scan_u:
	r := d.u4()
	if r < 0 {
		return "", d.mkError(ErrSyntax, "in unicode escape sequence")
	}

	// check for proceeding surrogate pair
	c = d.next()
	if !utf16.IsSurrogate(r) || c != '\\' {
		d.scratch.addRune(r)
		goto scan
	}
	if c = d.next(); c != 'u' {
		d.scratch.addRune(r)
		goto scan_esc
	}

	r2 := d.u4()
	if r2 < 0 {