for {
		r1, _, err := r.ReadRune()
		if err != nil {
			if err != io.EOF {
				t.Error("unexpected error on ReadRune:", err)
			}
			break
		}
		got += string(r1)
		// Put it back and read it again.
		if err = r.UnreadRune(); err != nil {
			t.Fatal("unexpected error on UnreadRune:", err)
		}
		r2, _, err := r.ReadRune()
		if err != nil {
			t.Fatal("unexpected error reading after unreading:", err)
		}

	VMOV	V10.S[0], V12.S[1]    // 4c050c6e
	VMOV	V9.H[0], V12.H[1]     // 2c05066e
	VMOV	V8.B[0], V12.B[1]     // 0c05036e
	VMOV	V8.B[7], V4.B[8]      // 043d116e

// CBZ
again:
	CBZ	R1, again // CBZ R1

// conditional operations
	CSET	GT, R1	        // e1d79f9a
	CSETW	HI, R2	        // e2979f1a
	CSEL	LT, R1, R2, ZR	// 3fb0829a
	CSELW	LT, R2, R3, R4	// 44b0831a

	// to _cgoCheckPointer, as done in checkIndex and checkAddr.
	//
	// When the function argument is a conversion to unsafe.Pointer,
	// we unwrap the conversion before checking the pointer,
	// and then wrap again when calling C.f. This lets us check
	// the real type of the pointer in some cases. See issue #25941.
	//
	// When the call to C.f is deferred, we use an additional function

	expect = "a to zed"
	if string(m) != expect {
		t.Errorf("rot13: expected %q got %q", expect, m)
	}

	// 5. Drop
	dropNotLatin := func(r rune) rune {
		if unicode.Is(unicode.Latin, r) {
			return r
		}
		return -1
	}
	m = Map(dropNotLatin, []byte("Hello, 세계"))
	expect = "Hello"
	if string(m) != expect {
		t.Errorf("drop: expected %q got %q", expect, m)
	}