def _selStrFromList(item_str, lst_str):
  """
  Selects a string from a list if it is a substring of the item.

  Parameters
  ----------
  item_str: str
      string for which the selection is done
  list_str: list-str
      list from which selection is done
  
  Returns
  -------
  str
  """
  strs = [s for s in lst_str if item_str == s]
  if len(strs) != 1:
    strs = [s for s in lst_str if s in item_str]
  if len(strs) != 1:
    raise ValueError("Cannot find %s uniquely in %s"
        % (item_str, str(lst_str)))
  return strs[0]