code: public static final  <T,W extends Unit<T>> Function1<? super T,? extends W> arrowUnit(Unit<?> w){
  
          return t-> (W)w.unit(t);
      }
docs: Use an existing instance of a type that implements Unit to create a KleisliM arrow for that type
  
  <pre>
  {@code
  Seq<Integer> myList = Seq.of(1,2,3);
  Fn1<? super String, ? extends Seq<String>> arrow = Functions.arrowUnit(myList);
  
  Seq<String> list = arrow.applyHKT("hello world");
  
  }
  </pre>
  
  @param w
  @param <T>
  @param <W>
  @return