pub(crate) fn lower_hex(bytes: impl AsRef<[u8]>) -> String {
const HEX: &[u8; 16] = b"0123456789abcdef";
let bytes = bytes.as_ref();
let mut out = String::with_capacity(bytes.len() * 2);
for byte in bytes {
out.push(HEX[(byte >> 4) as usize] as char);
out.push(HEX[(byte & 0x0f) as usize] as char);
}
out
}