class Falcon::Adapters::Response

def self.wrap(status, headers, body, request = nil)

@parameter request [Protocol::HTTP::Request] The original request.
@parameter body [Duck(:each, :close) | Nil] The rack response body.
@parameter headers [Duck(:each)] The rack response headers.
@parameter status [Integer] The rack response status.
Wrap a rack response. 
def self.wrap(status, headers, body, request = nil)
	headers, meta = wrap_headers(headers)
	
	if block = meta['rack.hijack']
		body = Async::HTTP::Body::Hijack.wrap(request, &block)
	else
		ignored = headers.extract(IGNORE_HEADERS)
		
		unless ignored.empty?
			Async.logger.warn("Ignoring protocol-level headers: #{ignored.inspect}")
		end
		
		body = Output.wrap(status, headers, body)
	end
	
	if request&.head?
		# I thought about doing this in Output.wrap, but decided the semantics are too tricky. Specifically, the various ways a rack response body can be wrapped, and the need to invoke #close at the right point.
		body = ::Protocol::HTTP::Body::Head.for(body)
	end
	
	protocol = meta['rack.protocol']
	
	# https://tools.ietf.org/html/rfc7231#section-7.4.2
	# headers.add('server', "falcon/#{Falcon::VERSION}")
	
	# https://tools.ietf.org/html/rfc7231#section-7.1.1.2
	# headers.add('date', Time.now.httpdate)
	
	return self.new(status, headers, body, protocol)
end