# File lib/merb-core/controller/mixins/responder.rb, line 350
    def content_type=(type)
      unless Merb.available_mime_types.has_key?(type)
        raise Merb::ControllerExceptions::NotAcceptable.new("Unknown content_type for response: #{type}") 
      end        
      headers['Content-Type'] = Merb.available_mime_types[type][:request_headers].first
      @_content_type = type
    end