# Write data as JSON and set the right content type header.
	fun json(json: nullable Serializable, status: nullable Int, plain, pretty: nullable Bool) do
		header["Content-Type"] = media_types["json"].as(not null)
		if json == null then
			send(null, status)
		else
			send(json.serialize_to_json(plain or else true, pretty or else false), status)
		end
	end