value<T> static method
接收者可以通过该函数获取消息中的数据
This function allows the receiver to get the data in the message
Implementation
static T? value<T>(String key) {
if (_textIsEmpty(key)) return null;
var value = instance()._map[key]?.value;
if (value == null) return null;
if (!(value is T)) {
debugPrintStack(
label: 'Error: value type [${value.runtimeType}] is not [$T]');
}
return value;
}