If two of the mugs are set on one tray.
return mugs ;return trays ;return #1 set on #2 ;return number of  #3 for each  #2 ;return #2 where  #4 is equal to  two ;return number of  #5 ;return if  #6 is equal to  one
['select', 'select', 'filter', 'group', 'comparative', 'aggregate', 'boolean']