Function press_for 

pub fn press_for<A: ActionSet>(
    keymap: &Keymap<A>,
    name: &str,
) -> Result<Press, String>

What presses the game’s action named name in keymap: its primary key (Keymap::primary), else its primary button (Keymap::primary_button). The one lookup of an action by name, so every tool presses an action as a player would. An error names the action: the game has none of that name, or it has neither a key nor a button.