has is_solution_state => (is => 'ro', required => 1);
+has on_exhaustion_step => (is => 'ro', required => 1);
+
sub next_proposition {
my ($self, $hyp) = @_;
$hyp ||= $self->current_hypothesis;
)
: ( is_solution_state => 1 )
),
+ on_exhaustion_step => undef,
);
}