def add_sub_idx(i1: int, change: int):
    """
    Adds or subtracts an index from another one and skips 0 if encountered.
    :param i1: The start index
    :param change: The change (+ or -)
    :return: The new index
    >>> add_sub_idx(-10, 10)
    1
    >>> add_sub_idx(10, -10)
    -1
    >>> add_sub_idx(-5, 10)
    6
    """
    return i1 + change + (1 if i1 < 0 < i1+change+1 else -1 if i1+change-1 < 0 < i1 else 0)