takac/vim-commandcaps — pull request #2 by tejr (2013-07-21 01:46:40+00:00)
Title: Zero to one arguments for :w and :wq

Vim does not allow writing to two files at once with :w and :wq:

:w test1.txt test2.txt
E172: Only one file name allowed

It's therefore more accurate to use -nargs=? rather than -nargs=*.