ixm_blocks-1.0.x-dev/modules/ixm_blocks_cards/ixm_blocks_cards.module

<?php

/**
 * @file
 * IXM Blocks Cards submodule.
 */

/**
 * Implements hook_theme().
 */
function ixm_blocks_cards_theme($existing, $type, $theme, $path) {
  return [
    'block__ixm_blocks_cards' => [
      'base hook' => 'block',
      'template' => 'block--ixm-blocks-cards',
    ],
  ];
}