\begin{definition}[Definition:Bourbaki Dangerous Bend Symbol]
The '''Bourbaki dangerous bend symbol''' is a symbol invented by the {{AuthorRef|Nicolas Bourbaki|Bourbaki group}} to warn the reader that there exists the serious possibility of making a common mistake while interpreting or utilising the material presented.
It was originally presented by {{AuthorRef|Nicolas Bourbaki|Bourbaki}}, as the pre-$1949$ French traffic road sign:
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Variants exist, notably {{AuthorRef|Donald Ervin Knuth}}'s version:
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{{NamedforDef|Nicolas Bourbaki|cat = Bourbaki}}
\end{definition}