Fix typo.

rhettinger · rhettinger · commit 9756f388c0f5 · 2003-09-10T00:11:28.000Z
diff --git a/Doc/lib/libos.tex b/Doc/lib/libos.tex
@@ -1080,7 +1080,7 @@ \subsection{Files and Directories \label{os-file-dir}}
 of its subdirectories (directories are generated bottom up).
 
 When \var{topdown} is true, the caller can modify the \var{dirnames} list
-in-place (perhaps unsing \keyword{del} or slice assignment), and
+in-place (perhaps using \keyword{del} or slice assignment), and
 \function{walk()} will only recurse into the subdirectories whose names
 remain in \var{dirnames}; this can be used to prune the search,
 impose a specific order of visiting, or even to inform \function{walk()}
