If 1 hyena with no prey in its mouth is walking toward the left.
return hyenas ;return mouth of #1 ;return prey ;return #1 where  #2 has #3 ;return #1 besides  #4 ;return #5 walking toward the  left ;return number of  #6 ;return if  #7 is equal to  one
['select', 'project', 'select', 'comparative', 'discard', 'filter', 'aggregate', 'boolean']