If there are four birds perched together in groups of two.
return birds ;return number of  #1 ;return if  #2 is equal to  four ;return #1 that are perched together in  groups ;return number of  #1 for each  #4 ;return #4 where  #5 is equal to  two ;return number of  #4 ;return number of  #6 ;return if  #7 is equal to  #8 ;return if  both  #3 and #9 are true
['select', 'aggregate', 'boolean', 'filter', 'group', 'comparative', 'aggregate', 'aggregate', 'boolean', 'boolean']