code: public <B> EvalT<W,B> flatMapT(final Function<? super T, EvalT<W,B>> f) {
          return of(run.map(Eval -> Eval.flatMap(a -> f.apply(a).run.stream()
                                                                        .toList()
                                                                        .get(0))));
      }
docs: Flat Map the wrapped Eval
  <pre>
  {@code
  EvalWT.of(AnyM.fromStream(Arrays.asEvalW(10))
  .flatMap(t->Eval.completedEval(20));
  
  
  //EvalWT<AnyMSeq<Stream<Eval[20]>>>
  }
  </pre>
  @param f FlatMap function
  @return EvalWT that applies the flatMap function to the wrapped Eval