def is_valid(sequence):
    """
    Returns "True" if the sequence is valid and "False" if the sequence is invalid.

    :param sequence: binary sequence
    :type sequence: string
    """
    # Is it binary?
    for digit in sequence:
        if digit not in '01':
            return False
    # Is the length greater than 8 digits?
    if len(sequence) > 8:
        return False

    return True