docs: function compare(hashstr, password, salt) {
    var iterations = arguments[3] === undefined ? 1024 : arguments[3];
    var keylen = arguments[4] === undefined ? 32 : arguments[4];
    var digest = arguments[5] === undefined ? 'sha256' : arguments[5];
    var encoding = arguments[6] === undefined ? 'hex' : arguments[6];
  
    return hash(password, salt, iterations, keylen, digest, encoding).then(function (data) {
      return hashstr === data;
    });
  }