import copy


def extend_dict(old_dict, new_dict):
    """
      Extend old_dict with entries in new_dict with keys not already in old_dict
    @param old_dict: dict to extend
    @param new_dict: dict with new entries to add
    @return:
      A completely new dict that is an extended version of old_dict with new_dict
    """
    if old_dict and new_dict:
        result_dict = copy.copy(new_dict)
        result_dict.update(old_dict)
        return result_dict
    elif old_dict:
        return copy.copy(old_dict)
    else:
        return {}