on = {
  -- for top-level handlers (see https://love2d.org/wiki/Main_Page for love.* variants)

  -- supported handlers:
  --   on.initialize (see love.load)
  --     One major note:
  --     driver.love gives you zero control over the order definitions are
  --     loaded in. To avoid issues, never initialize one global based on the
  --     value of another. Perform such initializations inside a function like
  --     on.initialize.
  --   on.quit
  --   on.code_change (runs after executing code received from the driver)
  --   on.code_submit (runs after submitting code to the app; only applicable to the driver, obviously)
  --   on.draw (avoid modifying global state here)
  --   on.update
  --   on.resize
  --   on.file_drop (see love.filedropped)
  --   on.focus
  --   on.mouse_press (see love.mousepressed)
  --   on.mouse_release (see love.mousereleased)
  --   on.mouse_move (see love.mousemoved)
  --   on.mouse_wheel_move (see love.wheelmoved)
  --   on.keychord_press (see keychord.lua in this repo)
  --   on.text_input (see love.textinput)
  --   on.key_release (see love.keyreleased)
  --   on.load_settings(settings)  -- fan out settings table into any other global state
                                   -- settings might be nil if there are no saved settings
                                   -- runs before on.initialize
  --   on.save_settings()  -- return a settings table which will be persisted to disk across restart
                           -- runs after on.quit
}