input: Write a function to sort a dictionary according to its values in descending order.
  
  def sortDictionary(dictionary):
    sorted_list = sorted(dictionary.items(), key=lambda x: x[1], reverse=True)
    sorted_dictionary = dict(sorted_list)
    return sorted_dictionary
  
  assert sortDictionary({'apple': 2, 'banana': 3, 'mango': 1}) == {'banana': 3, 'apple': 2, 'mango': 1}
  assert sortDictionary({'carrot': 5, 'grape': 4, 'pear': 6}) == {'pear': 6, 'carrot': 5, 'grape': 4}
  assert sortDictionary({}) == {}
  assert sortDictionary({'single': 1}) == {'single': 1}
output: def sortDictionary(dictionary):
    sorted_list = sorted(dictionary.items(), key=lambda x: x[1], reverse=True)
    sorted_dictionary = dict(sorted_list)
    return sorted_dictionary