docs: def find_and_filter_sgf_files(base_dir, min_year=None, komi=None):
      """Finds all sgf files in base_dir with year >= min_year and komi"""
      sgf_files = []
      for dirpath, dirnames, filenames in os.walk(base_dir):
          for filename in filenames:
              if filename.endswith('.sgf'):
                  path = os.path.join(dirpath, filename)
                  sgf_files.append(path)
  
      if min_year == komi == None:
          print ("Found {} sgf_files".format(len(sgf_files)))
          return sgf_files
  
      f = filter_year_komi(min_year, komi)
      filtered_sgf_files = [sgf for sgf in tqdm(sgf_files) if f(sgf)]
  
      print("{} of {} .sgf files matched (min_year >= {}, komi = {})".format(
          len(filtered_sgf_files), len(sgf_files), min_year, komi))
      return filtered_sgf_files