Fix various typos reported to python-docs.
diff --git a/Doc/ref/ref4.tex b/Doc/ref/ref4.tex
index f16dc8e..6e893f1 100644
--- a/Doc/ref/ref4.tex
+++ b/Doc/ref/ref4.tex
@@ -32,7 +32,7 @@
completed.
A \dfn{scope}\index{scope} defines the visibility of a name within a
-block. If a local variable is defined in a block, it's scope includes
+block. If a local variable is defined in a block, its scope includes
that block. If the definition occurs in a function block, the scope
extends to any blocks contained within the defining one, unless a
contained block introduces a different binding for the name. The