As humins we can reed mispelled werds but cumputrs can't. So we have to be very careful to tell it exactly what we want it to do. I recently spent an hour on each typo, trying to find what I had been doing wrong, when in fact It was one letter.
It's 'multiform' not mutliform'. It's food_list not foot_list. etc.
I almost feel like it was such a waste of time except I learned the important lesson to t y p e e v e r y t h i n g v e r y c a r e f u l l y .
I'm sure it will happen again but if nothings working and it should, check for typos!