Small clarification in docstring of dict.update(): the positional argument is not required.
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 79894e5..768351e 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -1973,9 +1973,9 @@
2-tuple; but raise KeyError if D is empty.");
PyDoc_STRVAR(update__doc__,
-"D.update(E, **F) -> None. Update D from dict/iterable E and F.\n"
-"If E has a .keys() method, does: for k in E: D[k] = E[k]\n\
-If E lacks .keys() method, does: for (k, v) in E: D[k] = v\n\
+"D.update([E, ]**F) -> None. Update D from dict/iterable E and F.\n"
+"If E present and has a .keys() method, does: for k in E: D[k] = E[k]\n\
+If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v\n\
In either case, this is followed by: for k in F: D[k] = F[k]");
PyDoc_STRVAR(fromkeys__doc__,