def header(content_type="text/html", filename=None):
	""" Return the header needed for a CGI application.
			@param content_type: The type of content delivered (optional, defaults to text/html)
			@param filename: Set the content to be a downloadable file (optional)
	"""
	output = "Content-Type: " + str(content_type) + "; charset=utf-8\n\n"
	if filename:
		output = "Content-Disposition: attachment; filename=" + filename + "\n" + output
	return output