refresh_token.diff

diff --git a/examples/oauth.ts b/examples/refresh_token.ts
index cc6d632..357e55d 100644
--- a/examples/oauth.ts
+++ b/examples/refresh_token.ts
@@ -62,6 +62,7 @@ let state: string | undefined
 // one eternity later, the user lands back on the redirect_uri
 // Authorization Code Grant Request & Response
 let access_token: string
+let refresh_token: string | undefined
 {
   // @ts-expect-error
   const currentUrl: URL = getCurrentUrl()
@@ -94,7 +95,7 @@ let access_token: string
   }
 
   console.log('Access Token Response', result)
-  ;({ access_token } = result)
+  ;({ access_token, refresh_token } = result)
 }
 
 // Protected Resource Request
@@ -115,3 +116,25 @@ let access_token: string
 
   console.log('Protected Resource Response', await response.json())
 }
+
+// Refresh Token Grant Request & Response
+if (refresh_token) {
+  const response = await oauth.refreshTokenGrantRequest(as, client, refresh_token)
+
+  let challenges: oauth.WWWAuthenticateChallenge[] | undefined
+  if ((challenges = oauth.parseWwwAuthenticateChallenges(response))) {
+    for (const challenge of challenges) {
+      console.error('WWW-Authenticate Challenge', challenge)
+    }
+    throw new Error() // Handle WWW-Authenticate Challenges as needed
+  }
+
+  const result = await oauth.processRefreshTokenResponse(as, client, response)
+  if (oauth.isOAuth2Error(result)) {
+    console.error('Error Response', result)
+    throw new Error() // Handle OAuth 2.0 response body error
+  }
+
+  console.log('Access Token Response', result)
+  ;({ access_token, refresh_token } = result)
+}