Make clear that tuple() accepts the same kind of arguments as list().
diff --git a/Doc/lib/libfuncs.tex b/Doc/lib/libfuncs.tex
index ec7ce86..acf1b09 100644
--- a/Doc/lib/libfuncs.tex
+++ b/Doc/lib/libfuncs.tex
@@ -722,7 +722,9 @@
\begin{funcdesc}{tuple}{sequence}
Return a tuple whose items are the same and in the same order as
-\var{sequence}'s items. If \var{sequence} is already a tuple, it
+\var{sequence}'s items. \var{sequence} may be a sequence, a
+container that supports iteration, or an iterator object.
+If \var{sequence} is already a tuple, it
is returned unchanged. For instance, \code{tuple('abc')} returns
returns \code{('a', 'b', 'c')} and \code{tuple([1, 2, 3])} returns
\code{(1, 2, 3)}.