def check(filename, content)
      @checkers.each do |checker|
        checker.check(filename, content) if checker.parse_file?(filename)
      end
    end
def check(filename, content)
      @checkers.each do |checker|
        checker.check(filename, content) if checker.parse_file?(filename)
      end
    end
check the ruby plain code.

 @param [String] filename is the filename of ruby code.
 @param [String] content is the content of ruby file.