def not_at_goal_set(trees):
    """convenience / readability function which returns the not terminated trees from a list

    :param trees: list of input trees
    :type trees: list
    :return: trees from the input list which are not terminated
    :rtype: list
    """
    not_at_goal = []
    for tree in trees:
        if not tree.terminated:
            not_at_goal.append(tree)
    return not_at_goal