Base class for keys events with modifiers.
Contains keys events information with modifiers support like [code]SHIFT[/code] or [code]ALT[/code]. See [method Node._input].
http://docs.godotengine.org/en/3.0/learning/features/inputs/inputevent.html
State of the Alt modifier.
State of the Command modifier.
State of the Ctrl modifier.
State of the Meta modifier.
State of the Shift modifier.