flatMap<S, R, E, A, B>  function 
 
        
StateReaderTaskEither<S, R, E, B>  Function(StateReaderTaskEither<S, R, E, A> )
flatMap<S, R, E, A, B>( 
    
    
- StateReaderTaskEither<S, R, E, B> f(- A a
 
Implementation
StateReaderTaskEither<S, R, E, B> Function(StateReaderTaskEither<S, R, E, A>)
    flatMap<S, R, E, A, B>(StateReaderTaskEither<S, R, E, B> Function(A a) f) =>
        (fa) => StateReaderTaskEither(
              fa.call.compose(RTE.flatMap((a) => f(a.first)(a.second))),
            );