# File lib/amq/protocol/client.rb, line 232
      def self.split_headers(user_headers)
        properties, headers = {}, {}
        user_headers.each do |key, value|
          # key MUST be a symbol since symbols are not garbage-collected
          if Basic::PROPERTIES.include?(key)
            properties[key] = value
          else
            headers[key] = value
          end
        end

        return [properties, headers]
      end