parse_content_type

# File actionmailer/lib/action_mailer/part_container.rb, line 43
      def parse_content_type(defaults=nil)
        if content_type.blank? 
          return defaults                                                ? 
            [ defaults.content_type, { 'charset' => defaults.charset } ] : 
            [ nil, {} ] 
        end 
        ctype, *attrs = content_type.split(/;\s*/)
        attrs = attrs.inject({}) { |h,s| k,v = s.split(/=/, 2); h[k] = v; h }
        [ctype, {"charset" => charset || defaults && defaults.charset}.merge(attrs)]
      end