code: def run_json(self):
          
          checks = {}
          for file in self.files:
              try:
                  results = self._check(file)
              except Error as e:
                  checks[file] = {
                      "error": e.msg
                  }
              else:
                  checks[file] = {
                      "score": results.score,
                      "comments": results.comment_ratio >= results.COMMENT_MIN,
                      "diff": "<pre>{}</pre>".format("\n".join(self.html_diff(results.original, results.styled))),
                  }
  
          json.dump(checks, sys.stdout, indent=4)
          print()
docs: Run checks on self.files, printing json object
          containing information relavent to the CS50 IDE plugin at the end.