If one boat is sailing to the right and the other is sailing to the left.
return boats ;return #1 sailing  to  the  right ;return #1 sailing  to  the  left ;return number of  #2 ;return number of  #3 ;return if  #4 is equal to  one ;return if  #5 is equal to  one ;return if  both  #6 and #7 are true
['select', 'filter', 'filter', 'aggregate', 'aggregate', 'boolean', 'boolean', 'boolean']