Return the argument list ID. This is a number which identifies the argument list being used. Zero is used for the global argument list. See arglist. Returns -1 if the arguments are invalid.

Without arguments use the current window. With {winnr} only use this window in the current tab page. With {winnr} and {tabnr} use the window in the specified tab page. {winnr} can be the window number or the window-ID.