TokenID(), not GetTokenID().
diff --git a/auth_results.go b/auth_results.go
index c8e7a55..1e501ae 100644
--- a/auth_results.go
+++ b/auth_results.go
@@ -7,5 +7,5 @@
 type AuthResults interface {
 
 	// Retrieve the authentication token's value from the authentication response.
-	GetTokenID() (string, error)
+	TokenID() (string, error)
 }