code: public static <R, T> Function<T, R> spy1st(Function<T, R> function, Box<T> param) {
          return spy(function, Box.<R>empty(), param);
      }
docs: Proxies a function spying for parameter.
  
  @param <R> the function result type
  @param <T> the function parameter type
  @param function the function that will be spied
  @param param a box that will be containing spied parameter
  @return the proxied function