Action:
    .doc: """
An abstract action that can be mapped to a key in a Control.Keyboard.Controller through a
Control.Keyboard.KeyBinding. Concrete variants control the exact behavior, see for example
Control.Keyboard.Actions.Once, Control.Keyboard.Action.Hold.

targets: The target input controls to send the value specified by the action to.
field_name: Optional field name for when the targets are not single field inputs.
"""
    targets is Physics.Signals.Input[]: []
    optional field_name is String
