import std.digest.sha : SHA1;
import std.string : representation;
string data1 = "Hello, world", data2 = "Hola mundo";
auto hmac = HMAC!SHA1("My s3cR3T keY".representation);
auto digest = hmac.put(data1.representation)
                  .put(data2.representation)
                  .finish();
static immutable expected = [
    197, 57, 52, 3, 13, 194, 13,
    36, 117, 228, 8, 11, 111, 51,
    165, 3, 123, 31, 251, 113];
assert(digest == expected);