docs: def matrix(ctx, scenario_name, subcommand):  # pragma: no cover
      """
      List matrix of steps used to test instances.
      """
  
      args = ctx.obj.get('args')
      command_args = {
          'subcommand': subcommand,
      }
  
      s = scenarios.Scenarios(
          base.get_configs(args, command_args), scenario_name)
      s.print_matrix()