return any integers N, N+1, and N-1

def nearIntegersPredicate(field):
    """return any integers N, N+1, and N-1"""
    ints = integers(field)
    near_ints = set()
    for char in ints:
        num = int(char)
        near_ints.add(str(num - 1))
        near_ints.add(str(num))
        near_ints.add(str(num + 1))

    return near_ints