listen method

@override String listen(String event, dynamic callback(Map<String, dynamic>))

Implementation

@override
String listen(String event, Function(Map<String, dynamic>) callback) {
  if (events[event] == null) {
    events[event] = {};
    events[event]["callbacks"] = [];
    events[event]["last"] = {};
  }

  List current = events[event]["callbacks"];
  String key = idGenerator();
  current.add({"key": key, "cb": callback});
  return key;
}