If there are two sinks, and none of them have legs.
return sinks ;return #1 that have legs ;return number of  #1 ;return number of  #2 ;return if  #3 is equal to  two ;return if  #4 is equal to  zero ;return if  both  #5 and #6 are true
['select', 'filter', 'aggregate', 'aggregate', 'boolean', 'boolean', 'boolean']