code: public <U> Try<U> flatMap(Function<? super V, Try<U>> mapper) {
          if (isSuccess()) {
              return mapper.apply(value);
          }
          return failed(this.throwable);
      }
docs: Flats maps the Try into another Try type
  
  @param mapper the flat map function
  @param <U>    the target type
  
  @return a new Try