def kill!(url)
      # normalize the url
      url = URI(url)

      # session key
      key = key_for(url)

      if (sess = @sessions[key])
        begin 
          sess.finish
        rescue IOError
        end

        @sessions.delete(key)
      end
    end
def kill!(url)
      # normalize the url
      url = URI(url)

      # session key
      key = key_for(url)

      if (sess = @sessions[key])
        begin 
          sess.finish
        rescue IOError
        end

        @sessions.delete(key)
      end
    end
Destroys an HTTP session for the given scheme, host and port.

 @param [URI::HTTP, String] url
   The URL of the requested session.

 @return [nil]

 @since 0.2.2