This is a small example of the 'notany' clause used to verify that none of
the elements of a list meet a certain requirement.  This is done in both
forward-chaining and backward-chaining rules.

The forward-chaining and backward-chaining rules are in two different .krb
files showing examples of use of the 'notany' clause in both cases.

These rules find all people who have no aunts all people with no uncles.

    >>> import test
    >>> test.fc_test()
    ... prints out everybody that doesn't have any step brothers or sisters ...
    >>> test.bc_test()
    ... prints out everybody that doesn't have any step brothers or sisters ...

