You should already be familiar with the ls command line tool.
Your task is to implement your own version of ls.
It must act the same as ls would, if run from the directory containing this README.md file, for the following command lines:
ls -1ls -1 sample-filesls -1 -a sample-files
Matching any additional behaviours or flags are optional stretch goals.
We recommend you start off supporting just -1, then adding support for -a.