code: def mime_type(instance):
      
      mime_pattern = re.compile(r'^(application|audio|font|image|message|model'
                                '|multipart|text|video)/[a-zA-Z0-9.+_-]+')
      for key, obj in instance['objects'].items():
          if ('type' in obj and obj['type'] == 'file' and 'mime_type' in obj):
              if enums.media_types():
                  if obj['mime_type'] not in enums.media_types():
                      yield JSONError("The 'mime_type' property of object '%s' "
                                      "('%s') should be an IANA registered MIME "
                                      "Type of the form 'type/subtype'."
                                      % (key, obj['mime_type']), instance['id'],
                                      'mime-type')
              else:
                  info("Can't reach IANA website; using regex for mime types.")
                  if not mime_pattern.match(obj['mime_type']):
                      yield JSONError("The 'mime_type' property of object '%s' "
                                      "('%s') should be an IANA MIME Type of the"
                                      " form 'type/subtype'."
                                      % (key, obj['mime_type']), instance['id'],
                                      'mime-type')
docs: Ensure the 'mime_type' property of file objects comes from the Template
      column in the IANA media type registry.