Optionally allow unknows to become negative.
tree453d2f6e010e845cfb04db86e20561e85fb76da7
-rw-r--r-- 15008 LICENSE
-rw-r--r-- 4171 README
drwxr-xr-x - autoconf
drwxr-xr-x - doc
drwxr-xr-x - example
drwxr-xr-x - include
drwxr-xr-x - source
drwxr-xr-x - test