class Sinatra::Response

def finish
  @body = block if block_given?
  if [204, 304].include?(status.to_i)
    header.delete "Content-Type"
    [status.to_i, header.to_hash, []]
  else
    body = @body || []
    body = [body] if body.respond_to? :to_str
    if header["Content-Length"].nil? && body.respond_to?(:to_ary)
      header["Content-Length"] = body.to_ary.
        inject(0) { |len, part| len + part.length }.to_s
    end
    [status.to_i, header.to_hash, body]
  end
end