Update the Client Credentials Example for v4 (#1346)

Author: sirosen

docs/examples/client_credentials.rst

@@ -46,13 +46,15 @@ The shortest version of the flow looks like this:
     # the secret, loaded from wherever you store it
     CLIENT_SECRET = "..."
 
-    client = globus_sdk.ConfidentialAppAuthClient(CLIENT_ID, CLIENT_SECRET)
-    token_response = client.oauth2_client_credentials_tokens()
+    confidential_client = globus_sdk.ConfidentialAppAuthClient(CLIENT_ID, CLIENT_SECRET)
+    token_response = confidential_client.oauth2_client_credentials_tokens(
+        requested_scopes=globus_sdk.TransferClient.scopes.all
+    )
 
     # the useful values that you want at the end of this
-    globus_auth_data = token_response.by_resource_server["auth.globus.org"]
-    globus_transfer_data = token_response.by_resource_server["transfer.api.globus.org"]
-    globus_auth_token = globus_auth_data["access_token"]
+    globus_transfer_data = token_response.by_resource_server[
+        globus_sdk.TransferClient.resource_server
+    ]
     globus_transfer_token = globus_transfer_data["access_token"]
 
 
@@ -69,9 +71,9 @@ For example, after running the code above,
 
     authorizer = globus_sdk.AccessTokenAuthorizer(globus_transfer_token)
     tc = globus_sdk.TransferClient(authorizer=authorizer)
-    print("Endpoints Belonging to {}@clients.auth.globus.org:".format(CLIENT_ID))
+    print(f"Endpoints Belonging to {CLIENT_ID}@clients.auth.globus.org:")
     for ep in tc.endpoint_search(filter_scope="my-endpoints"):
-        print("[{}] {}".format(ep["id"], ep["display_name"]))
+        print(f"[{ep['id']}] {ep['display_name']}")
 
 Note that we're doing a search for "my endpoints", but we refer to the results
 as belonging to ``<CLIENT_ID>@clients.auth.globus.org``. The "current user" is
@@ -81,8 +83,7 @@ Handling Token Expiration
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 
 When you get access tokens, you also get their expiration time in seconds.
-You can inspect the ``globus_transfer_data`` and ``globus_auth_data``
-structures in the example to see.
+You can inspect the ``globus_transfer_data`` structure in the example to see.
 
 Tokens should have a long enough lifetime for any short-running operations
 (less than a day).
@@ -104,20 +105,20 @@ Use it like so:
 
     import globus_sdk
 
-    # you must have a client ID
+    # you must have a client ID and secret
     CLIENT_ID = "..."
-    # the secret, loaded from wherever you store it
     CLIENT_SECRET = "..."
 
     confidential_client = globus_sdk.ConfidentialAppAuthClient(
         client_id=CLIENT_ID, client_secret=CLIENT_SECRET
     )
-    scopes = "urn:globus:auth:scope:transfer.api.globus.org:all"
-    cc_authorizer = globus_sdk.ClientCredentialsAuthorizer(confidential_client, scopes)
+    cc_authorizer = globus_sdk.ClientCredentialsAuthorizer(
+        confidential_client, globus_sdk.TransferClient.scopes.all
+    )
     # create a new client
     tc = globus_sdk.TransferClient(authorizer=cc_authorizer)
 
     # usage is still the same
-    print("Endpoints Belonging to {}@clients.auth.globus.org:".format(CLIENT_ID))
+    print(f"Endpoints Belonging to {CLIENT_ID}@clients.auth.globus.org:")
     for ep in tc.endpoint_search(filter_scope="my-endpoints"):
-        print("[{}] {}".format(ep["id"], ep["display_name"]))
+        print(f"[{ep['id']}] {ep['display_name']}")