If I didn't take a look at the typedef, I'd think that _ws is a class, because the type name is a noun. Maybe a verb would be clearer? The same applies to the variable name here and below. That said, I'm not sure what is a general practice in Dart. In C++, predicates are everywhere, but in C++ `()` is pefectly possible for a class - in Dart it's not, so `_something()` is more of a surprise than `_doSomething()`. Feel free to ignore this rant :)