# File lib/faraday/builder.rb, line 90
    def use(klass, *args, &block)
      if klass.is_a? Symbol
        use_symbol(Faraday::Middleware, klass, *args, &block)
      else
        raise_if_locked
        @handlers << self.class::Handler.new(klass, *args, &block)
      end
    end