}
	for len(sa) > 0 {
		ss = append(ss, uniqueA+sa[0])
		sa = sa[1:]
	}
	for len(sb) > 0 {
		ss = append(ss, uniqueB+sb[0])
		sb = sb[1:]
	}
	return strings.Join(ss, "\n")
}

func TestWriter(t *testing.T) {
	type (
		testHeader struct { // WriteHeader(hdr) == wantErr
			hdr     Header
			wantErr error
		}
		testWrite struct { // Write(str) == (wantCnt, wantErr)
			str     string
			wantCnt int