Please consider not using hardcoded vars e.g $content.
A much cleaner solution would be something like $this->layout()->output();
Using as hardcoded var name could be a security issue e.g
Let's say that someone have register_global_vars on, then $content could be set through the URL
IMHO, hardcoded vars and global vars is 'bad' practice - I know that it improves performance but it can compromise security