Core walker class to output an unordered list of category checkbox input elements.

Ends the element output, if needed.

Ends the list of after the elements are added.

Start the element output.

Starts the list before the elements are added.

Ensures a string is a valid SQL ‘order by’ clause.

Outputs an unordered list of checkbox input elements labeled with category names.

Outputs a link category checklist element.

Filters the published time of the post.