    # File lib/rack/utils.rb, line 327
        def delete_cookie_header!(header, key, value = {})
          case header["Set-Cookie"]
          when nil, ''
            cookies = []
          when String
            cookies = header["Set-Cookie"].split("\n")
          when Array
            cookies = header["Set-Cookie"]
          end

          cookies.reject! { |cookie|
            if value[:domain]
              cookie =~ /\A#{escape(key)}=.*domain=#{value[:domain]}/
            elsif value[:path]
              cookie =~ /\A#{escape(key)}=.*path=#{value[:path]}/
            else
              cookie =~ /\A#{escape(key)}=/
            end
          }

          header["Set-Cookie"] = cookies.join("\n")

          set_cookie_header!(header, key,
                     {:value => '', :path => nil, :domain => nil,
                       :max_age => '0',
                       :expires => Time.at(0) }.merge(value))

          nil
        end