function verified(err, user, info) {
    if (err) { return self.error(err); }
    if (!user) { return self.fail(info); }
    self.success(user, info);
  }
Authenticate request by verifying username and password.

This function is protected, and should not be called directly.  Instead,
use `passport.authenticate()` middleware and specify the {@link Strategy#name `name`}
of this strategy and any options.

@protected
@param {http.IncomingMessage} req - The Node.js {@link https://nodejs.org/api/http.html#class-httpincomingmessage `IncomingMessage`}
         object.
@param {Object} [options]
@param {string} [options.badRequestMessage='Missing credentials'] - Message
         to display when a request does not include a username or password.
         Used in conjunction with `failureMessage` or `failureFlash` options.

@example
passport.authenticate('local');