docs: def get_final_numbers(filename, out_dir):
      """Copy the final_files file and get the number of markers and samples.
  
      :param filename: the name of the file.
      :param out_dir: the output directory.
  
      :type filename: str
      :type out_dir: str
  
      :returns: the final number of markers and samples
      :rtype: tuple
  
      """
      # Copying the file
      shutil.copy(filename, out_dir)
  
      # Reading the number of markers and samples
      nb_samples = None
      nb_markers = None
      with open(filename, "r") as i_file:
          for line in i_file:
              row = line.rstrip("\r\n").split("\t")
              if len(row) == 1:
                  continue
              path, ext = os.path.splitext(row[0])
              if ext in {".bim", ".tped", ".map"}:
                  nb_markers = row[1]
              elif ext in {".fam", ".ped", ".tfam"}:
                  nb_samples = row[1]
  
      assert nb_samples
      assert nb_markers
  
      return nb_markers, nb_samples