code: public GrantsFilter withPage(int pageNumber, int amountPerPage) {
          parameters.put("page", pageNumber);
          parameters.put("per_page", amountPerPage);
          return this;
      }
docs: Filter by page
  
  @param pageNumber    the page number to retrieve.
  @param amountPerPage the amount of items per page to retrieve.
  @return this filter instance