def take_0_k_th_from_2D_list(obj_list, k=0, verbose=False):
    """returns the element obj_list[0][k] if obj_list is a nested list of depth 2, or obj_list otherwise."""
    if isinstance(obj_list, list):
        if verbose:
            print("obj_list is:", obj_list)
        if isinstance(obj_list[0], list):
            return obj_list[0][k]
        else:
            er = "obj_list is a list but not a 2D list"
            raise Exception(er)
    else:
        return obj_list