import std.conv : to;

assert(42.to!string(16, LetterCase.upper) == "2A");
assert(42.to!string(16, LetterCase.lower) == "2a");

import std.digest.hmac : hmac;
import std.digest : toHexString;
import std.digest.sha : SHA1;
import std.string : representation;

const sha1HMAC = "A very long phrase".representation
    .hmac!SHA1("secret".representation)
    .toHexString!(LetterCase.lower);
assert(sha1HMAC == "49f2073c7bf58577e8c9ae59fe8cfd37c9ab94e5");