How to use the openid.realm function in openid

}
  
  // Google+
  if (options.requestVisibleActions) {
    // Space separated list of allowed app actions
    // as documented at:
    //  https://developers.google.com/+/web/app-activities/#writing_an_app_activity_using_the_google_apis_client_libraries
    //  https://developers.google.com/+/api/moment-types/
    params['request_visible_actions'] = options.requestVisibleActions;
  }
  
  // OpenID 2.0 migration
  if (options.openIDRealm) {
    // This parameter is needed when migrating users from Google's OpenID 2.0 to OAuth 2.0
    //   https://developers.google.com/accounts/docs/OpenID?hl=ja#adjust-uri
    params['openid.realm'] = options.openIDRealm;
  }
  
  // Undocumented
  if (options.approvalPrompt) {
    params['approval_prompt'] = options.approvalPrompt;
  }
  if (options.userID) {
    // Undocumented, but supported by Google's OAuth 2.0 endpoint.  Appears to
    // be equivalent to `login_hint`.
    params['user_id'] = options.userID;
  }
  
  return params;
}

if (options.display) {
    // Specify what kind of display consent screen to display to users.
    //   https://developers.google.com/accounts/docs/OpenIDConnect#authenticationuriparameters
    params['display'] = options.display;
  }
  if (options.requestVisibleActions) {
    // Space separated list of allowed app actions
    // as documented at:
    //  https://developers.google.com/+/web/app-activities/#writing_an_app_activity_using_the_google_apis_client_libraries
    //  https://developers.google.com/+/api/moment-types/
    params['request_visible_actions'] = options.requestVisibleActions;
  }
  if (options.openIDRealm) {
    // This parameter is needed when migrating users from Google's OpenID 2.0 to OAuth 2.0
    //   https://developers.google.com/accounts/docs/OpenID?hl=ja#adjust-uri
    params['openid.realm'] = options.openIDRealm;
  }
  return params;
}

}

  // Google+
  if (options.requestVisibleActions) {
    // Space separated list of allowed app actions
    // as documented at:
    //  https://developers.google.com/+/web/app-activities/#writing_an_app_activity_using_the_google_apis_client_libraries
    //  https://developers.google.com/+/api/moment-types/
    params['request_visible_actions'] = options.requestVisibleActions.join(' ');
  }

  // OpenID 2.0 migration
  if (options.openIDRealm) {
    // This parameter is needed when migrating users from Google's OpenID 2.0 to OAuth 2.0
    //   https://developers.google.com/accounts/docs/OpenID?hl=ja#adjust-uri
    params['openid.realm'] = options.openIDRealm;
  }

  return params;
}

if(assoc_handle)
  {
    params['openid.assoc_handle'] = assoc_handle;
  }

  if(returnUrl)
  {
    // Value should be missing if RP does not want
    // user to be sent back
    params['openid.return_to'] = returnUrl;
  }

  if(realm)
  {
    if(provider.version.indexOf('2.0') !== -1) {
      params['openid.realm'] = realm;
    }
    else {
      params['openid.trust_root'] = realm;
    }
  }
  else if(!returnUrl)
  {
    return callback({ message: 'No return URL or realm specified' });
  }

  callback(null, _buildUrl(provider.endpoint, params));
}

if(assoc_handle)
  {
    params['openid.assoc_handle'] = assoc_handle;
  }

  if(returnUrl)
  {
    // Value should be missing if RP does not want
    // user to be sent back
    params['openid.return_to'] = returnUrl;
  }

  if(realm)
  {
    if(provider.version.indexOf('2.0') !== -1) {
      params['openid.realm'] = realm;
    }
    else {
      params['openid.trust_root'] = realm;
    }
  }
  else if(!returnUrl)
  {
    return callback({ message: 'No return URL or realm specified' });
  }

  callback(null, _buildUrl(provider.endpoint, params));
}

}
  
  // Google+
  if (options.requestVisibleActions) {
    // Space separated list of allowed app actions
    // as documented at:
    //  https://developers.google.com/+/web/app-activities/#writing_an_app_activity_using_the_google_apis_client_libraries
    //  https://developers.google.com/+/api/moment-types/
    params['request_visible_actions'] = options.requestVisibleActions;
  }
  
  // OpenID 2.0 migration
  if (options.openIDRealm) {
    // This parameter is needed when migrating users from Google's OpenID 2.0 to OAuth 2.0
    //   https://developers.google.com/accounts/docs/OpenID?hl=ja#adjust-uri
    params['openid.realm'] = options.openIDRealm;
  }
  
  // Undocumented
  if (options.approvalPrompt) {
    params['approval_prompt'] = options.approvalPrompt;
  }
  if (options.userID) {
    // Undocumented, but supported by Google's OAuth 2.0 endpoint.  Appears to
    // be equivalent to `login_hint`.
    params['user_id'] = options.userID;
  }
  
  return params;
}