Fix example usage of Proto optionals

Author: magnesj

docs/source/generate_protobuf_docs.py

@@ -575,10 +575,8 @@ def _generate_usage_examples(self) -> str:
     if entry.HasField('saturation'):
         saturation_value = entry.saturation
     else:
-        saturation_value = None
+        saturation_value = "1*"
 
-    # Or use getattr with a default value
-    saturation = getattr(entry, 'saturation', None)
 
 Working with Vec3d and Vec3i
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