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