import collections
lst_dict = [{"name" : "Tom", "age" : 35},
{"name" : "Alma", "age" : 40},
{"name" : "Isla" , "age" : 27}]
lst_dict = sorted(lst_dict, key = lambda v: v['age'], reverse=True)
print(lst_dict)
'''
run:
[{'name': 'Alma', 'age': 40}, {'name': 'Tom', 'age': 35}, {'name': 'Isla', 'age': 27}]
'''