code: def read_dir(path, folder):
      
      full_path = os.path.join(path, folder)
      fnames = glob(f"{full_path}/*.*")
      directories = glob(f"{full_path}/*/")
      if any(fnames):
          return [os.path.relpath(f,path) for f in fnames]
      elif any(directories):
          raise FileNotFoundError("{} has subdirectories but contains no files. Is your directory structure is correct?".format(full_path))
      else:
          raise FileNotFoundError("{} folder doesn't exist or is empty".format(full_path))
docs: Returns a list of relative file paths to `path` for all files within `folder`