If all of the birds sit on a branch with a blue background behind them.
return birds ;return branch ;return background behind #1 ;return #3 that is blue ;return #1 that sit on #2 ;return #5 that has #4 ;return number of  #1 ;return number of  #6 ;return if  #7 is equal to  #8
['select', 'select', 'project', 'filter', 'filter', 'filter', 'aggregate', 'aggregate', 'boolean']