If there are two zebras, one adult and one child facing right.
return zebras ;return #1 that is adult ;return #1 that is child ;return #2 that is facing right ;return #3 that is facing right ;return number of  #1 ;return if  #6 is equal to  two ;return number of  #4 ;return number of  #5 ;return if  #8 is equal to  one ;return if  #9 is equal to  one ;return if  both  #10 and #11 are true ;return if  both  #7 and #12 are true
['select', 'filter', 'filter', 'filter', 'filter', 'aggregate', 'boolean', 'aggregate', 'aggregate', 'boolean', 'boolean', 'boolean', 'boolean']