docs: def cmd_list(unused_conf: Config):
      """Print out information on loaded builders and hooks."""
      for name, builder in sorted(Plugin.builders.items()):
          if builder.func:
              print('+- {0:16s} implemented in {1.__module__}.{1.__name__}()'
                    .format(name, builder.func))
          else:
              print('+- {0:16s} loaded with no builder function'.format(name))
          for hook_name, hook_func in sorted(Plugin.get_hooks_for_builder(name)):
              print('  +- {0} hook implemented in '
                    '{1.__module__}.{1.__name__}()'
                    .format(hook_name, hook_func))