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