docs: def update_ld_api(project: str, environment: str, feature: str, state: str):
      """
      Execute command against the LaunchDarkly API.
  
      This command is generally not used directly, instead it is called as a
      part of running the ``playback()`` function.
  
      :param project: LaunchDarkly project key.
      :param environment: LaunchDarkly environment key.
      :param feature: LaunchDarkly feature key.
      :param state: State for a feature flag.
      """
      ld_api = LaunchDarklyApi(
          os.environ.get('LD_API_KEY'),
          project,
          environment
      )
  
      if valid_state(state):
          if state.lower() == 'off':
              new_state = False
          else:
              new_state = True
          ld_api.update_flag(new_state, feature)
      else:
          raise ValueError('Invalid state: {0}, -s needs to be either \
              on or off.'.format(state))