If non-snow-covered evergreens and a flat horizon are behind one of the sled dog teams.
return sled dog teams ;return evergreens ;return #2 that are non-snow-covered ;return horizon ;return #4 that is flat ;return #1 with #3 behind ;return #1 with #5 behind ;return #1 in  both  #6 and #7 ;return number of  #8 ;return if  #9 is equal to  one
['select', 'select', 'filter', 'select', 'filter', 'filter', 'filter', 'intersection', 'aggregate', 'boolean']