def update(<EOL>self, person_group_id, name=None, user_data=None, custom_headers=None, raw=False, **operation_config):
body = models.NameAndUserDataContract(name=name, user_data=user_data)<EOL>url = self.update.metadata['<STR_LIT:url>']<EOL>path_format_arguments = {<EOL>'<STR_LIT>': self._serialize.url("<STR_LIT>", self.config.endpoint, '<STR_LIT:str>', skip_quote=True),<EOL>'<STR_LIT>': self._serialize.url("<STR_LIT>", person_group_id, '<STR_LIT:str>', max_length=<NUM_LIT:64>, pattern=r'<STR_LIT>')<EOL>}<EOL>url = self._client.format_url(url, **path_format_arguments)<EOL>query_parameters = {}<EOL>header_parameters = {}<EOL>header_parameters['<STR_LIT:Content-Type>'] = '<STR_LIT>'<EOL>if custom_headers:<EOL><INDENT>header_parameters.update(custom_headers)<EOL><DEDENT>body_content = self._serialize.body(body, '<STR_LIT>')<EOL>request = self._client.patch(url, query_parameters, header_parameters, body_content)<EOL>response = self._client.send(request, stream=False, **operation_config)<EOL>if response.status_code not in [<NUM_LIT:200>]:<EOL><INDENT>raise models.APIErrorException(self._deserialize, response)<EOL><DEDENT>if raw:<EOL><INDENT>client_raw_response = ClientRawResponse(None, response)<EOL>return client_raw_response<EOL><DEDENT>
Update an existing person group's display name and userData. The
        properties which does not appear in request body will not be updated.

        :param person_group_id: Id referencing a particular person group.
        :type person_group_id: str
        :param name: User defined name, maximum length is 128.
        :type name: str
        :param user_data: User specified data. Length should not exceed 16KB.
        :type user_data: str
        :param dict custom_headers: headers that will be added to the request
        :param bool raw: returns the direct response alongside the
         deserialized response
        :param operation_config: :ref:`Operation configuration
         overrides<msrest:optionsforoperations>`.
        :return: None or ClientRawResponse if raw=true
        :rtype: None or ~msrest.pipeline.ClientRawResponse
        :raises:
         :class:`APIErrorException<azure.cognitiveservices.vision.face.models.APIErrorException>`