If there is a single human feeding a pelican with white and black feathers.
return human ;return pelican ;return feathers of #2 ;return #2 where  #3 are black and white ;return #1 feeding #4 ;return number of  #5 ;return if  #6 is equal to  one
['select', 'select', 'project', 'comparative', 'filter', 'aggregate', 'boolean']