policyDBPrefix          = "policydb/"
	policyDBUsersListKey    = "policydb/users/"
	policyDBSTSUsersListKey = "policydb/sts-users/"
	policyDBGroupsListKey   = "policydb/groups/"
)

func findSecondIndex(s string, substr string) int {
	first := strings.Index(s, substr)
	if first == -1 {
		return -1
	}
	second := strings.Index(s[first+1:], substr)
	if second == -1 {
		return -1
	}