[Bug #1209880] Describe only the True/False return values from lock.acquire()
diff --git a/Doc/lib/libthreading.tex b/Doc/lib/libthreading.tex
index 5b50a22..3526974 100644
--- a/Doc/lib/libthreading.tex
+++ b/Doc/lib/libthreading.tex
@@ -167,8 +167,7 @@
Acquire a lock, blocking or non-blocking.
When invoked without arguments, block until the lock is
-unlocked, then set it to locked, and return. There is no
-return value in this case.
+unlocked, then set it to locked, and return true.
When invoked with the \var{blocking} argument set to true, do the
same thing as when called without arguments, and return true.