code: def language_contents(instance):
      
      if instance['type'] != 'language-content' or 'contents' not in instance:
          return
  
      for key, value in instance['contents'].items():
          if key not in enums.LANG_CODES:
              yield JSONError("Invalid key '%s' in 'contents' property must be"
                              " an RFC 5646 code" % key, instance['id'])
          for subkey, subvalue in value.items():
              if not PROPERTY_FORMAT_RE.match(subkey):
                  yield JSONError("'%s' in '%s' of the 'contents' property is "
                                  "invalid and must match a valid property name"
                                  % (subkey, key), instance['id'], 'observable-dictionary-keys')
docs: Ensure keys in Language Content's 'contents' dictionary are valid
      language codes, and that the keys in the sub-dictionaries match the rules
      for object property names.