docs: def _load_patterns(self, folders, pattern_dict=None):
          """Load all pattern from all the files in folders"""
          if pattern_dict is None:
              pattern_dict = {}
          for folder in folders:
              for file in os.listdir(folder):
                  if regex.match('^[\w-]+$', file):
                      self._load_pattern_file(os.path.join(folder, file), pattern_dict)
          return pattern_dict