@GoogleCloudBaseHook.fallback_to_default_project_id<EOL><INDENT>def get_instance(self, instance_id, project_id=None):<DEDENT>
instance = self._get_client(project_id=project_id).instance(instance_id)<EOL>if not instance.exists():<EOL><INDENT>return None<EOL><DEDENT>return instance<EOL>
Retrieves and returns the specified Cloud Bigtable instance if it exists.
Otherwise, returns None.

:param instance_id: The ID of the Cloud Bigtable instance.
:type instance_id: str
:param project_id: Optional, Google Cloud Platform project ID where the
    BigTable exists. If set to None or missing,
    the default project_id from the GCP connection is used.
:type project_id: str