Drupal 8 - Change fields elements in form using hook_form_alter

Code snippet that can be used to change a field element in form using hook_form_alter in Drupal 8.

/**
 * @param $form
 * @param $form_state
 * @param $form_id
 */
function mytheme_form_alter(&$form, &$form_state, &$form_id)
{
    if ($form_id == 'FORM_ID'){

//            to remove  description      
            unset($form['name']['#description']);

//            to update title 
            $form['name']['#title'] = t("Your Custom name");

//            to update placeholder
            $form['name']['#attributes']['placeholder'] = 'Custom placeholder';

//            to add class
            $form['name']['#attributes']['class'][] = 'custom_class';

//            to add class to submit button
            $form['actions']['submit']['#attributes']['class'][] = 'submit_class';

//            to change value of submit button
            $form['actions']['submit']['#attributes']['value'][] = t('Submit Value');

//            to add prefix 
            $form['actions']['submit']['#prefix'] = '<div class="class_div_prefix">';

//            to add suffix
            $form['actions']['submit']['#suffix'] = '</div>';

//           to update All option with your text
           $form['field_name']['#options']['All'] = t('Select option'); 
    }
}