title: how to implement hook_theme drupal 8?
body: <p>Im new to drupal,I need to render a form so i have to implement hook theme, my confusion is Under which directory I should create hook theme file in drupal 8?</p>
  
  <pre><code>// my_module.module
  
  function custom_module_theme($existing, $type, $theme, $path) {
        return array(
           'customize_form' =&gt; array(
           'variables' =&gt; array(
           'Custom_Form' =&gt; NULL
          ),
         'render element' =&gt; 'form'
        ),
      );
  }
  </code></pre>
  
  <p>where I have to put above file in drupal 8??</p>
  
  <p>Thanks in advance.</p>