WordPress: Custom post type columns with array insert

custom-post-type-columns-array-insert.php

function array_insert($array, $values, $offset) {
	// http://stackoverflow.com/questions/1783089/array-splice-for-associative-arrays/11114956#11114956
	return array_slice($array, 0, $offset, true) + $values + array_slice($array, $offset, NULL, true);
}

function admin_columns($columns) {
	// this is the 'manage_edit-{post-type}_columns' filter
	// add_filter( 'manage_edit-' . self::$post_type . '_columns', array($this, 'admin_columns'), 10, 1 ) ;
	$columns = array_insert($columns, array('sales-channel' => 'Sales Channel'), 2);
	return $columns;
}