Hi Emanuel,

I did some further tests and found that the "function *** is not known
to be defined" error only happen once for either a undefined function
or a function defined in a nested structure, as seen in the attached
screenshot.

1. The kkl0-fun, which is defined at top-level, linter shows no error
   at all about it
2. The kkl1-fun is defined as long as the *kk0l* global variable 
   is assigned as t
3. The first linter error appears when the kkl1-fun is called first
   time
4. At the second call-site of kkl1-fun, the linter "undefined-unction"
   error disappears 
5. the kkl2-fun is totally undefined, and linter identifies the
   undefined function error at its first call-site
6. at the second call-site of kkl2-fun, the undefined-function linter
   error disappears as well

So, it seems that elint starts to ignore undefined function starting
second call-site regardless that function is defined or not. we need
some further investigation on elint.el's elint-update-env function and
related functions.

Thanks,
Kiong-Gē.