<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def list_instances(self):
 """List instances owned by the project. For example: .. literalinclude:: snippets.py :start-after: [START bigtable_list_instances] :end-before: [END bigtable_list_instances] :rtype: tuple :returns: (instances, failed_locations), where 'instances' is list of :class:`google.cloud.bigtable.instance.Instance`, and 'failed_locations' is a list of locations which could not be resolved. """

        resp = self.instance_admin_client.list_instances(self.project_path)
        instances = [Instance.from_pb(instance, self) for instance in resp.instances]
        return instances, resp.failed_locations