Brad Warren <bradmwarren@gmail.com> added the comment: Thanks for the help! I was mistaken here. The behavior I want is to not add the option to the namespace regardless of whether or not the user set it. I was initially under the impression that dest=SUPPRESS caused this behavior, however, it seems to have the same behavior as default=SUPPRESS due to the code at https://github.com/python/cpython/blob/711381dfb09fbd434cc3b404656f7fd306161.... By using default=SUPPRESS which is documented and a custom __call__ method on an Action class, I can get the behavior I want so I'm closing this issue. Thanks again and sorry for the noise! ---------- stage: -> resolved status: open -> closed _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue42650> _______________________________________