input: Write a function to sort a dictionary according to its values in descending order and return the sorted dictionary.
  
  assert sortDictionary({'apple': 2, 'banana': 3, 'mango': 1}) == {'banana': 3, 'apple': 2, 'mango': 1}
  assert sortDictionary({'a': 10, 'b': 5, 'c': 20}) == {'c': 20, 'a': 10, 'b': 5}
  assert sortDictionary({'x': 7, 'y': 7, 'z': 7}) == {'x': 7, 'y': 7, 'z': 7}
output: def sortDictionary(d):
      return {k: v for k, v in sorted(d.items(), key=lambda item: item[1], reverse=True)}