/// Creates a new instance using the provided key, skipping the salt
/// and persona. This method is equivalent to calling
/// [`new_with_salt_and_personal`](Self::new_with_salt_and_personal)
/// with empty slices for the salt and persona.
 #[inline]
pub fn new_with_key(key: &[u8]) -> Result<Self, InvalidLength> {
 Self::new_with_salt_and_personal(key, &[], &[])
}

use blake2::Blake2bMac;
use blake2::digest::{Update, FixedOutput, consts::U16};
use hex_literal::hex;
let mut hasher: Blake2bMac<U16> = Blake2bMac::new_with_key(b"my_key").unwrap();
hasher.update(b"my_input");
let res = hasher.finalize_fixed();
assert_eq!(res.as_ref(), hex!("3c3869ce1c58d0569827a731d8eab099"));

use blake2::VarBlake2b;
use blake2::digest::{Update, VariableOutput};
use hex_literal::hex;
let mut hasher = VarBlake2b::new_keyed(b"my_key", 16);
hasher.update(b"my_input");
let res = hasher.finalize_boxed();
assert_eq!(res.as_ref(), hex!("3c3869ce1c58d0569827a731d8eab099"));