.HMAC!: ClassType
.HMAC!.
    digest_size: Nat
    block_size: Nat
    name: Str
    update!: (self: RefMut(.HMAC!), msg: Bytes) => NoneType
    digest: (self: Ref(.HMAC!)) -> Bytes
    hexdigest: (self: Ref(.HMAC!)) -> Str
    copy: (self: Ref(.HMAC!)) -> .HMAC!

.compare_digest: (a: Str or Bytes, b: Str or Bytes) -> Bool
.new: (key: Bytes, msg := Bytes, digestmod := Str or GenericCallable or GenericModule) -> .HMAC!
.digest: (key: Bytes, msg := Bytes, digest := Str or GenericCallable or GenericModule) -> Bytes