Find the ids of the nurses who are on call in block floor 1 and block code 1.
return nurses ;return #1 who are on call ;return block floors of #2 ;return #2 where #3 is  1 ;return block  codes of #2 ;return #2 where #5 is  1 ;return ids of both #4 and #6
['select', 'filter', 'project', 'comparative', 'project', 'comparative', 'intersection']