class Sinatra::Base

def invoke(&block)
  res = catch(:halt) { instance_eval(&block) }
  return if res.nil?
  case
  when res.respond_to?(:to_str)
    @response.body = [res]
  when res.respond_to?(:to_ary)
    res = res.to_ary
    if Fixnum === res.first
      if res.length == 3
        @response.status, headers, body = res
        @response.body = body if body
        headers.each { |k, v| @response.headers[k] = v } if headers
      elsif res.length == 2
        @response.status = res.first
        @response.body   = res.last
      else
        raise TypeError, "#{res.inspect} not supported"
      end
    else
      @response.body = res
    end
  when res.respond_to?(:each)
    @response.body = res
  when (100..599) === res
    @response.status = res
  end
  res
end