After super method in the child class, I am unable to pass a parameter value to the parent class.

Forgive me if I get any terminology incorrect. I’m quite new to Dart and especially generics in Dart. However, I don’t understand why I get an error with the following code.

I have code like this:

I want to connect my android emulator to a node js local server running localhost:2000, I searched and found a way to do it but it does not work.
The local host name in the settings of the emulator takes localhost so I used localhost as the host name, i tried using the ip address of the laptop but it invalid proxy

Почему когда телефон в кармане раблокируется, хоть функция в кармане включена. Подскажите пожалуйста как можно это исправить.
Спасибо

I was used to this function

I want to specify a time series as essentially a List of (double, double) pairs; but I’d like to abstract the doubles to the more meaningful types, datetime and value. But Dart objects. It complains (on the last line of code) that neither (datetime, value), i.e., a pair of types, nor dartx Pair(datetime, value) is a type, so neither can serve as a generic type parameter to the List type. What’s the right way to express what I want to say here — to pass a pair type to the list type builder?

I’m new to dart. I want to specify a time series as a List of (double, double) pairs; but I’d like to abstract the doubles to the more meaningful types, datetime and value, each is then defined as double. But Dart objects: neither (datetime, value), a pair of types, nor dartx Pair(datetime, value) is a type, so neither can serve as a generic type parameter to the List type. What’s the right way to express what I want to say here? Thank you.

The following fails:

Error