def shift(lattice, start: int):
    """Shift lattice periodically so that it starts at index 'start'.

    Args:
        lattice (any iterable): a list of objects.
        start (int): index of first element in new lattice.

    Returns:
        new_lattice: shifted lattice.

    """
    leng = len(lattice)
    start = int(start)
    start = max(min(start, leng), -leng)
    if start < 0:
        start += leng
    new_lattice = lattice[start:]
    for i in range(start):
        new_lattice.append(lattice[i])
    return new_lattice