docs: public <R1, R2, R4> Writer<W,R4> forEach3(Function<? super T, ? extends Writer<W,R1>> value2,
                                                 BiFunction<? super T, ? super R1, ? extends Writer<W,R2>> value3,
                                                 Function3<? super T, ? super R1, ? super R2, ? extends R4> yieldingFunction) {
  
          return this.flatMap(in -> {
  
              Writer<W,R1> a = value2.apply(in);
              return a.flatMap(ina -> {
                  Writer<W,R2> b = value3.apply(in,ina);
                  return b.map(in2 -> {
                      return yieldingFunction.apply(in, ina, in2);
  
                  });
  
  
  
              });
  
          });
  
      }