Parse token expiration from the response.
diff --git a/auth_results.go b/auth_results.go
index 1e501ae..07e0fc7 100644
--- a/auth_results.go
+++ b/auth_results.go
@@ -1,5 +1,7 @@
 package gophercloud
 
+import "time"
+
 // AuthResults encapsulates the raw results from an authentication request. As OpenStack allows
 // extensions to influence the structure returned in ways that Gophercloud cannot predict at
 // compile-time, you should use type-safe accessors to work with the data represented by this type,
@@ -8,4 +10,7 @@
 
 	// Retrieve the authentication token's value from the authentication response.
 	TokenID() (string, error)
+
+	// ExpiresAt retrieves the token's expiration time.
+	ExpiresAt() (time.Time, error)
 }