ffffix ttttypo

Co-authored-by: bendn <[email protected]>

Author: saethlin

src/policy/unsafe-preconditions.md

@@ -1,6 +1,6 @@
 # Runtime checks for preconditions of `unsafe fn`
 
-When possible, a debug assertion for the preconditions of an `unsafe fn` should be added inside the body of said function, bbefore the implementation exploits the precondition.
+When possible, a debug assertion for the preconditions of an `unsafe fn` should be added inside the body of said function, before the implementation exploits the precondition.
 
 The compiler supports two kinds of debug assertions. Those that branch on `cfg(debug_assertions)` such as `debug_assert!` or `debug_assert_nounwind!` will be compiled out of the standard library distributed by rustup. Such checks are still valuable to add because they can be used by external tools like [cargo-careful](https://crates.io/crates/cargo-careful) or [cargo-fuzz](https://crates.io/crates/cargo-fuzz), users of `-Zbuild-std` or just our own CI (because it enables both optimizations and debug assertions).