# Nothing special about these:
sub add_son_father_pair { die "NYI" }
sub delete_son_father_pair { die "NYI" }
sub get_a_father { die "NYI" }
sub output_hash_neatly { die "NYI" }
sub replace_a_father { die "NYI" }
sub get_a_grandfather { die "NYI" }

# I wanted a bit more detail about this one, though.
sub add_daily_task { die "NYI";
   my ($task_name, $day_of_week, $task) = @_;
   # Dies on error, otherwise returns $time_of_day the task is scheduled for
}