class Falcon::Adapters::Response

This wrapper takes those issues into account and adapts the rack response tuple into a {Protocol::HTTP::Response}.
- Other ‘rack.` specific header key/value pairs.
- Newline-separated header values.
- Potentially invalid body when processing a `HEAD` request.
- Potentially invalid content length.
- A `headers` callback which bypasses normal response handling.
A Rack response consisting of `[status, headers, body]` includes various rack-specific elements, including:
A wrapper for a `Rack` 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

def self.wrap_headers(fields)

@returns [Tuple(Protocol::HTTP::Headers, Hash)]
Process the rack response headers into into a {Protocol::HTTP::Headers} instance, along with any extra `rack.` metadata. 
def self.wrap_headers(fields)
	headers = ::Protocol::HTTP::Headers.new
	meta = {}
	
	fields.each do |key, value|
		key = key.downcase
		
		if key.start_with?('rack.')
			meta[key] = value
		else
			value.to_s.split("\n").each do |part|
				headers.add(key, part)
			end
		end
	end
	
	return headers, meta
end

def initialize(status, headers, body, protocol = nil)

@parameter protocol [String] The response protocol for upgraded requests.
@parameter body [Protocol::HTTP::Body] The response body.
@parameter headers [Protocol::HTTP::Headers] The response headers.
@parameter status [Integer] The response status.
Initialize the response wrapper. 
def initialize(status, headers, body, protocol = nil)
	super(nil, status, headers, body, protocol)
end