Help me learn

So i am using a date picker component from ng2-bootstrap, I’m slowly rewriting it to understand everything thats going on…

public constructor(@Self() cd:NgModel) { = cd;
    cd.valueAccessor = this;
    return this

So whats happening here? I don’t understand

Have you considered the ionic 2 date time picker?

I have, but i still like to learn.
i understand that cd is of type NgModel but i don’t understand what the @Self() decorator really means. = cd
Assigns the NgModel to the variable cd.
cd.valueAccessor = this
assigns the valueAccessor the entire class??
so the class is assigned itself as a variable?
I’m returning the class in the constructor? what?