docs: def resource_listdir(package_or_requirement, relative_path):
      """
      Similar to pkg_resources.resource_listdir but if the resource it not found via pkg_resources
      it also looks in a predefined list of paths in order to find the resource
  
      :param package_or_requirement: the module in which the resource resides
      :param relative_path: the relative path to the resource
      :return: a list of all files residing in the target path
      :rtype: list
      """
      path = resource_filename(package_or_requirement, relative_path)
      only_files = [f for f in listdir(path) if isfile(join(path, f))]
      return only_files