normalize_callback_params

# File activesupport/lib/active_support/callbacks.rb, line 594
      def normalize_callback_params(filters, block) # :nodoc:
        type = CALLBACK_FILTER_TYPES.include?(filters.first) ? filters.shift : :before
        options = filters.extract_options!
        filters.unshift(block) if block
        [type, filters, options.dup]
      end