public function test_equals()
 {
     $weekDef_iso = WeekFields::ISO();
     $weekDef_sundayStart = WeekFields::SUNDAY_START();
     $this->assertTrue($weekDef_iso->equals(WeekFields::of(DayOfWeek::MONDAY(), 4)));
     $this->assertTrue($weekDef_sundayStart->equals(WeekFields::of(DayOfWeek::SUNDAY(), 1)));
     //$this->assertEquals($weekDef_iso->hashCode(), WeekFields::of(DayOfWeek::MONDAY(), 4)->hashCode());
     // $this->assertEquals($weekDef_sundayStart->hashCode(), WeekFields::of(DayOfWeek::SUNDAY(), 1)->hashCode());
     $this->assertFalse($weekDef_iso->equals($weekDef_sundayStart));
     //$this->assertNotEquals($weekDef_iso->hashCode(), $weekDef_sundayStart->hashCode());
 }