copy(head, in)
	}
	tail = head[len(in):]
	return
}

// ringCompressAndEncode1 appends a 32-byte encoding of a ring element to s,
// compressing one coefficients per bit.
//
// It implements Compress₁, according to FIPS 203 (DRAFT), Definition 4.5,
// followed by ByteEncode₁, according to FIPS 203 (DRAFT), Algorithm 4.
func ringCompressAndEncode1(s []byte, f ringElement) []byte {
	s, b := sliceForAppend(s, encodingSize1)