@Test public void number() { assertEquals(123, light.number()); }
public int number() { return number; }
Light { public int number() { return number; } }
Light { public int number() { return number; } Light(int number); }
Light { public int number() { return number; } Light(int number); boolean isOn(); int number(); void turnOff(); void turnOn(); }
Light { public int number() { return number; } Light(int number); boolean isOn(); int number(); void turnOff(); void turnOn();  }