title: How to loop through all the files in a folder (if the names of the files are unknown)?
body: <p>There is a folder: <code>C:\\Users\..myfolder</code></p>
  
  <p>It contains <code>.pdf</code> files (or any other, say .csv). I cannot change the names of those files, and I do not know the number of those files. I need to loop all of the files one by one.
  How can I do this? </p>
  
  <p>(I know how to do this if I knew the names)</p>