|context> => |context: shopping basket>

|f> => 3|apple> + 5|oranges> + |milk> + |bread> + |coffee> + |steak>
basket |f> => 3|apple> + 5|oranges> + |milk> + |bread> + |coffee> + |steak>

basket |user 1> => |milk> + |bread> + |tea> + |bananas> + |carrots> + |chocolate>

basket |user 2> => 4|apple> + |milk> + |coffee> + |steak>

basket |user 3> => |chocolate> + |vegemite> + |olive oil> + |pizza> + |cheese>

basket |user 4> => |vegemite> + |cheese> + |bread> + |salami>