code: def delete
        i = 0
        loop do
          logger.info("deletion loop iteration #{i}")
          i += 1
  
          return unless anything_to_delete?
  
          criteria.each do |table, selection|
            delete_selection(table, selection)
          end
        end
      end
docs: criteria is of form [['users', "name = 'andrew'"], ['comments', 'id NOT IN (1, 2, 3)']]