Fatal error: Uncaught Error: Attempt to assign property "postcomment" on null in /home/pat/website/public/math/teaching/2013-spring-dynamics/homework.inc:69 Stack trace: #0 /home/pat/website/public/math/teaching/2013-spring-dynamics/homework.php(10): include_once() #1 {main} thrown in /home/pat/website/public/math/teaching/2013-spring-dynamics/homework.inc on line 69