code: def load_basic_system_bindings():
      
      registry = Registry()
  
      suspend_supported = Condition(
          lambda cli: suspend_to_background_supported())
  
      @registry.add_binding(Keys.ControlZ, filter=suspend_supported)
      def _(event):
          """
          Suspend process to background.
          """
          event.cli.suspend_to_background()
  
      return registry
docs: Basic system bindings (For both Emacs and Vi mode.)