We can't do this, because it means that people can create feeds or take action with a GET request. Below, `$did_post` is only used for argument validation -- but never actually used for "okay, should we allow the user to take actions?"

I think that dropping POST and GET arguments into the same variable is usually an easy way to have security problems, so I'd recommend against it. I'd just recommend having two modes for the page... if the user `$did_post`, do these actions, else, do these.