code: public static <T1, T2, R1, R2, R> Mono<R> forEach3(Mono<? extends T1> value1,
              Function<? super T1, ? extends Mono<R1>> value2,
              BiFunction<? super T1, ? super R1, ? extends Mono<R2>> value3,
              Function3<? super T1, ? super R1, ? super R2, ? extends R> yieldingFunction) {
  
          Future<? extends R> res = Future.fromPublisher(value1).flatMap(in -> {
  
              Future<R1> a = Future.fromPublisher(value2.apply(in));
              return a.flatMap(ina -> {
                  Future<R2> b = Future.fromPublisher(value3.apply(in, ina));
  
  
                  return b.map(in2 -> yieldingFunction.apply(in, ina, in2));
  
  
              });
  
          });
          return Mono.from(res);
  
      }
docs: Perform a For Comprehension over a Mono, accepting 2 generating functions.
  This results in a three level nested internal iteration over the provided Monos.
  
  <pre>
  {@code
  
  import static cyclops.companion.reactor.Monos.forEach3;
  
  forEach3(Mono.just(1),
  a-> Mono.just(a+1),
  (a,b) -> Mono.<Integer>just(a+b),
  Tuple::tuple)
  
  }
  </pre>
  
  @param value1 top level Mono
  @param value2 Nested Mono
  @param value3 Nested Mono
  @param yieldingFunction Generates a result per combination
  @return Mono with a combined value generated by the yielding function