How to enable “secondary playfield” flippers

Related Config File Sections
flippers:

Secondary or upper flippers (e.g. on an upper playfield) are enabled and defined just like normal lower flipper.

This is an example:

flippers:
   lower_left:
       main_coil: c_flipper_lower_left_main
       activation_switch: s_flipper_left
       label: Left Main Flipper
   lower_right:
       main_coil: c_flipper_lower_right_main
       activation_switch: s_flipper_right
       label: Right Main Flipper
   upper_left:
       main_coil: flipperUpLMain
       activation_switch: flipperUpL
       enable_events: ball_started, enable_upper_flippers
       disable_events: ball_will_end, service_mode_entered, disable_upper_flippers
       label: Upper Left Flipper
   upper_right:
       main_coil: flipperUpRMain
       activation_switch: flipperUpR
       enable_events: ball_started, enable_upper_flippers
       disable_events: ball_will_end, service_mode_entered, disable_upper_flippers
       label: Upper Right Flipper

Additionally, we defined disable_upper_flippers as event to disable the upper flippers and enable_upper_flippers to re-enable them. This might be useful if you want to disable flippers in some mode. If you do not want them to be enabled by default remove ball_started from enable_events.