# File lib/mime/content_types.rb, line 87
    def file_type file
      filename = file.respond_to?(:path) ? file.path : file
      extension = File.extname(filename)[1..-1] # array index removes period
      typ_exts = CONTENT_TYPES.find {|type, extentions| extentions.include? extension}
      typ_exts ? typ_exts.first : typ_exts      # returns +type+ from above or nil
    end