// FindFirstVersionHistoryIndexByVersionHistoryItem find the first VersionHistory index which contains the given version history item.
func FindFirstVersionHistoryIndexByVersionHistoryItem(h *historyspb.VersionHistories, item *historyspb.VersionHistoryItem) (int32, error) {
version_histories.go
for versionHistoryIndex, history := range h.Histories {
if ContainsVersionHistoryItem(history, item) {
return int32(versionHistoryIndex), nil
}