Find the average age of the students who have allergies with food and animal types.
return students ;return #1 who  have  allergies ;return #2 with  food ;return #2 with  animals ;return #3 ,   #4 ;return the ages of  #5 ;return the average of  #6
['select', 'filter', 'filter', 'filter', 'union', 'project', 'aggregate']