def _add_pending(self, rpc):
    assert not isinstance(rpc, MultiRpc)
    self.__pending_rpcs.add(rpc)
https://familysearch.org/developers/docs/api/tree/Person_Change_History_resource
dataset/ETHPy150Open GoogleCloudPlatform/python-compat-runtime/appengine-compat/exported_appengine_sdk/google/appengine/datastore/datastore_rpc.py/BaseConnection._add_pending--crossover with--dataset/ETHPy150Open AmEv7Fam/familysearch-python-sdk-opensource/familysearch/changeHistory.py/ChangeHistory.person_change_history