If there is a total of 1 buffalo in water up to their head.
return buffaloes ;return water ;return head of #1 ;return #2 up to  #3 ;return #1 in  #4 ;return number of  #5 ;return if  #6 is equal to  one
['select', 'select', 'project', 'filter', 'filter', 'aggregate', 'boolean']