GetFields.
        Returns information for all fields.
        :param str project: Project ID or project name
        :param str expand: Use ExtensionFields to include extension fields, otherwise exclude them. Unless the feature flag for this parameter is enabled, extension fields are always included.
        :rtype: [WorkItemField]

def get_fields(self, project=None, expand=None):
        """GetFields.
        Returns information for all fields.
        :param str project: Project ID or project name
        :param str expand: Use ExtensionFields to include extension fields, otherwise exclude them. Unless the feature flag for this parameter is enabled, extension fields are always included.
        :rtype: [WorkItemField]
        """
        route_values = {}
        if project is not None:
            route_values['project'] = self._serialize.url('project', project, 'str')
        query_parameters = {}
        if expand is not None:
            query_parameters['$expand'] = self._serialize.query('expand', expand, 'str')
        response = self._send(http_method='GET',
                              location_id='b51fd764-e5c2-4b9b-aaf7-3395cf4bdd94',
                              version='5.0',
                              route_values=route_values,
                              query_parameters=query_parameters)
        return self._deserialize('[WorkItemField]', self._unwrap_collection(response))