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

	// 3. Rot13
	m = Map(rot13, []byte("a to zed"))
	expect = "n gb mrq"
	if string(m) != expect {
		t.Errorf("rot13: expected %q got %q", expect, m)
	}

	// 4. Rot13^2
	m = Map(rot13, Map(rot13, []byte("a to zed")))
	expect = "a to zed"
	if string(m) != expect {

EF,SpE2kRN,SoEzkRQ,eAAA,gBAEF,SpE2kRN,SoEzkRQ,aAAA,gBAfF,QAAgC,QAAA,eAChC,SpE8lRN,SoE5lRQ,YAAA,eAEF,SpE8lRN,SoE5lRQ,cAAA,eAEF,SpE8lRN,SoE5lRQ,eAAA,eAEF,SpE8lRN,SoE5lRQ,aAAA,eAfF,QAAgC,QAAA,iBAChC,SpEinRN,SoE/mRQ,YAAA,iBAEF,SpEinRN,SoE/mRQ,cAAA,iBAEF,SpEinRN,SoE/mRQ,eAAA,iBAEF,SpEinRN,SoE/mRQ,aAAA,iBAfF,QAAgC,QAAA,eAChC,SpEooRN,SoEloRQ,YAAA,eAEF,SpEooRN,SoEloRQ,cAAA,eAEF,SpEooRN,SoEloRQ,eAAA,eAEF,SpEooRN,SoEloRQ,aAAA,eAQF,SAAwB,OAAA,kBACxB,UpEgoRN,UoE9nRQ,WAAA,kBAEF,UpEgoRN,UoE9nRQ,aAAA,kBAEF,UpE...