I have existing code creating a custom WP cli command. The purpose of the code is to change a parent page for a custom post type. However, I don’t know how to read this code to understand what command exactly I should run to do this. I get the invalid parent error all the time.

So if I have a custom post type called event and I want to set all single events to have a parent page that has an ID of 12, what should I run?

<?php
$set_parents = function( $args = [], $assoc_args = [] ) {
  $arguments = wp_parse_args( $assoc_args, array(
    'post-type'   => 'post',
    'parent'    => null
  ) );

  if(is_null($arguments['parent']) && is_numeric(intval($arguments['parent']))) {
    WP_CLI::error( " invalid parent ");
  }
  else {
    $count = setParentsOnPostType($arguments['post-type'], $arguments['parent']);
    
    WP_CLI::success( "$count ".$arguments['post-type']." -posts set to child of ".$arguments['parent'] );
  }

};

function setParentsOnPostType($post_type, $parent_id = 0) {
  $counter = 0;
  $ok = true;

  $args = [
    'post_type'     => $post_type,
    'posts_per_page' => -1,
  ];
  $query = new WP_Query($args);
  
  if($query->have_posts()) { // if we have posts, then we update data
    
    while($query->have_posts()) {
      $query->the_post();
      wp_update_post([
        'ID' => get_the_ID(), 
        'post_parent' => $parent_id
      ]);

      $counter++;
    }
    wp_reset_postdata();
  }
  return $counter;
}

if ( defined( 'WP_CLI' ) && WP_CLI ) {
  WP_CLI::add_command( 'set-parents', $set_parents );
}

I have tried several combinations like
wp set-parents post-type=event 12
wp set-parents post_type=event parent_id=12
wp set-parents event 12

But really, I have no idea what command I should use as I’m not really familiar with custom WP cli commands so I’m just guessing here.