Adding example with ``not`` for ``if``

I could not find an example with ``not``, so I added it here.
minor #1581 Adding example with ``not`` for ``if`` (InFog)

This PR was merged into the 1.16-dev branch.

Discussion
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Adding example with ``not`` for ``if``

I could not find an example with ``not``, so I added it here.

Commits
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4a75e40 Adding example with ``not`` for ``if``