Fix three latent bugs in samples/explore_workbook.py

Fresh-eyes review on #1843 (2026-09-17) surfaced three pre-existing
bugs that the samples/_shared.py migration in that PR did not
introduce but did make more visible:

1. Line 127 used a bare type annotation `changed: TSC.CustomViewItem(
   id=c.id, name=...)` instead of an assignment, so `changed` was never
   bound and the following `server.custom_views.update(changed)` would
   NameError.
2. `c` was defined inside the custom-views loop and then referenced
   outside it. On a site with zero custom views the loop never runs
   and every subsequent reference NameErrors.
3. `if args.delete:` at line 145 referred to a flag that was never
   defined in the sample's argparse, so any invocation reaching that
   line raised AttributeError.

Fixes:
- Add `=` on line 127 to bind `changed`.
- Collect the custom-views iterator into a list, wrap the update/
  export block in `if custom_views:`, and pick the last entry
  explicitly (`c = custom_views[-1]`) — matches the intent of the
  original "for the last custom view in the list" comment.
- Add a `--delete` argparse flag with `action="store_true"` and a
  clear help string. Guard the delete block so it prints a clear
  no-op message when the site has no custom views.

No other behavior change. Sample compiles and imports cleanly.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jacalata

samples/explore_workbook.py

@@ -30,6 +30,11 @@ def main():
     parser.add_argument(
         "--powerpoint", "-ppt", metavar="FILENAME", help="filename (a .ppt file) to save the powerpoint deck"
     )
+    parser.add_argument(
+        "--delete",
+        action="store_true",
+        help="delete the last custom view on the site after the update/export demo",
+    )
 
     args = parser.parse_args()
 
@@ -117,23 +122,26 @@ def main():
 
             # Get custom views. `.get()` only returns the first page;
             # use TSC.Pager to iterate every custom view on the site.
-            for c in TSC.Pager(server.custom_views):
+            custom_views = list(TSC.Pager(server.custom_views))
+            for c in custom_views:
                 print(c)
 
-            # for the last custom view in the list
+            if custom_views:
+                # For the last custom view in the list.
+                c = custom_views[-1]
 
-            # update the name
-            # note that this will fail if the name is already changed to this value
-            changed: TSC.CustomViewItem(id=c.id, name="I was updated by tsc")
-            verified_change = server.custom_views.update(changed)
-            print(verified_change)
+                # update the name
+                # note that this will fail if the name is already changed to this value
+                changed = TSC.CustomViewItem(id=c.id, name="I was updated by tsc")
+                verified_change = server.custom_views.update(changed)
+                print(verified_change)
 
-            # export as image. Filters etc could be added here as usual
-            server.custom_views.populate_image(c)
-            filename = c.id + "-image-export.png"
-            with open(filename, "wb") as f:
-                f.write(c.image)
-            print("saved to " + filename)
+                # export as image. Filters etc could be added here as usual
+                server.custom_views.populate_image(c)
+                filename = c.id + "-image-export.png"
+                with open(filename, "wb") as f:
+                    f.write(c.image)
+                print("saved to " + filename)
 
             if args.powerpoint:
                 # Populate workbook preview image
@@ -143,9 +151,12 @@ def main():
                 print(f"\nDownloaded powerpoint of workbook to {os.path.abspath(args.powerpoint)}")
 
             if args.delete:
-                print(f"deleting {c.id}")
-                unlucky = TSC.CustomViewItem(c.id)
-                server.custom_views.delete(unlucky.id)
+                if not custom_views:
+                    print("--delete requested but no custom views on this site; nothing to delete.")
+                else:
+                    print(f"deleting {c.id}")
+                    unlucky = TSC.CustomViewItem(c.id)
+                    server.custom_views.delete(unlucky.id)
 
 
 if __name__ == "__main__":