$ ls -al a_real_dir
total 4
drwxr-xr-x 1 ken None 0 Nov 19 18:20 .
drwxr-xr-x 1 ken None 0 Nov 19 19:10 ..
-rw-r--r-- 1 ken None 0 Nov 19 18:20 demo_file_A
-rw-r--r-- 1 ken None 0 Nov 19 18:20 demo_file_B

$ ls -al not_a_real_dir
ls: cannot access 'not_a_real_dir': No such file or directory