def trivial(target):
    """
    Return True if target is irreducible, False if reducible
    or None if undecidable.

    This trivial function checks the followings:
    (1) if the constant term is zero, the polynomial is reducible.
    (2) if not (1) and the degree is <= 1, the polynomial is irreducible.
    """
    if not target[0]:
        return False
    elif target.degree() <= 1:
        return True
    else:
        return None