1. DomName('Selection.modify')
  2. DocsEditable()
  3. Experimental()
void modify(String alter, String direction, String granularity)

Source 

@DomName('Selection.modify')
@DocsEditable()
@Experimental() // non-standard
void modify(String alter, String direction, String granularity) => _blink.BlinkSelection.instance.modify_Callback_3_(this, alter, direction, granularity);