MarcWeber/vim-addon-manager — comment on commit 77ffeec287a0ee13fa701272d3c65c4c0aed351f
File: autoload/vam/install.vim line 290
By ZyX-I:

> Thanks about filewriteable()

I also used to make this mistake (filewrit[]able, not filewrit*e*able), as well as enviro[]ment (enviro*n*ment). It is something you should always remember.