init method
Initialize using your lean cloud application info.
These fields can be found in lean cloud console -> {your application} -> Settings -> App keys.
Implementation
static void init(
{@required String appID, @required String appKey, @required serverUrl}) {
_instance = LCFBUtil._();
_feedbackBaseUrl = '$serverUrl/feedback';
_headers = {'X-LC-Id': appID, 'X-LC-Key': appKey};
_client = http.Client();
}