Input validation for nested dict and sorting list of tuples

[BashBedlam]

Here's another way to go about it.

tester = {'Afghanistan': {'Gold': 0, 'Silver': 0, 'Bronze': 2, 'Total': 2}, 'Albania': {'Gold': 0, 'Silver': 0, 'Bronze': 0, 'Total': 0}, 'Algeria': {'Gold': 5, 'Silver': 4, 'Bronze': 8, 'Total': 17}}

def rank_countries(dict1):
	if isinstance(dict1, dict):
		for i in dict1:
			if isinstance(dict1[i], dict):
				new_list = [(k, v['Total']) for k, v in dict1.items()]
				new_list=sorted(new_list, key= lambda tup: tup[1], reverse= True) 
				for rank in range (len (new_list)) :
					new_list [rank] = (rank+1,) + new_list [rank]
				return new_list
			else :
				return 'Input must be a nested dictionary.'
	else :
		return 'Input must be a nested dictionary.'

print (rank_countries (tester))

Output:
[(1, 'Algeria', 17), (2, 'Afghanistan', 2), (3, 'Albania', 0)]