code: @NotNull
      public Exceptional<T> ifPresent(@NotNull Consumer<? super T> consumer) {
          if (throwable == null) {
              consumer.accept(value);
          }
          return this;
      }
docs: Invokes consumer function with value if present.
  
  @param consumer  a consumer function
  @return this {@code Exceptional}
  @since 1.1.2