To everyone who writes parser hooks: be aware there is a breaking change
in 1.11.0.
Previously, if you wrote a parser hook function that does not return a
value, it could still appear to work. Now, any page that uses such a
function will blow up. (With an informative error message.)
I think it's a good change. But it means that everyone should carefully
regression-test their custom extensions after installing 1.11.0.
DanB