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<p>Language extensions can be very useful, but only if you know you can depend
-on them. In order to allow fine-grain features checks, we support two builtin
+on them. In order to allow fine-grain features checks, we support three builtin
function-like macros. This allows you to directly test for a feature in your
code without having to resort to something like autoconf or fragile "compiler
version checks".</p>