This gist is used in the tutorial https://www.vijayan.in/how-to-create-custom-table-list-in-wordpress-admin-page

column_cb.php

<?php
...
	/**
	 * Column cb.
	 *
	 * @param  array $item Item data.
	 * @return string
	 */
	public function column_cb( $item ) {
		return sprintf(
			'<input type="checkbox" name="%1$s_id[]" value="%2$s" />',
			esc_attr( $this->_args['singular'] ),
			esc_attr( $item['id'] )
		);
	}
  ...