def attachment(filename = nil, disposition = :attachment)
			content_dis = 'Content-Disposition'
			response[content_dis] = disposition.to_s
			return unless filename

			response[content_dis] << "; filename=\"#{File.basename(filename)}\""
			ext = File.extname(filename)
			response.content_type = ext unless ext.empty?
		end
def attachment(filename = nil, disposition = :attachment)
			content_dis = 'Content-Disposition'
			response[content_dis] = disposition.to_s
			return unless filename

			response[content_dis] << "; filename=\"#{File.basename(filename)}\""
			ext = File.extname(filename)
			response.content_type = ext unless ext.empty?
		end
Set the Content-Disposition to "attachment" with the specified filename,
 instructing the user agents to prompt to save,
 and set Content-Type by filename.
 @param filename [String, nil] filename of attachment
 @param disposition [Symbol, String] main content for Content-Disposition
 @example Set Content-Disposition header without filename
   attachment
 @example Set Content-Disposition header with filename and Content-Type
   attachment 'style.css'