give me the flights from new york to las vegas and memphis to las vegas on sunday 
return flights ;return #1 from  new york ;return #2 to las  vegas ;return #1 from  memphis ;return #4 to las  vegas ;return #2 on  sunday ;return #5 on  sunday ;return #6,  #7
['select', 'filter', 'filter', 'filter', 'filter', 'filter', 'filter', 'union']