code: public static <T1, T2, T3, R> FluentFunctions.FluentTriFunction<T1, T2, T3, R> ofChecked(final CheckedTriFunction<T1, T2, T3, R> fn) {
  
          return new FluentTriFunction<>(
                                         softenTriFunction(fn));
      }
docs: Convert a CheckedTriFunction to a FluentTriFunction
  <pre>
  {@code
  FluentFunctions.ofChecked(this::exceptionalFirstTime)
  .println()
  .retry(2,500)
  .applyHKT("hello","woo!","h")
  
  }
  </pre>
  @param fn CheckedTriFunction to convert
  @return FluentTriFunction