input: Write a function to sort a dictionary according to its values in descending order. If the input dictionary is empty, the function should return an empty dictionary.
  
  def sortDictionary(dictionary):
    if not dictionary:
      return {}
    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({})=={}
output: def sortDictionary(dictionary):
    if not dictionary:
      return {}
    sorted_list = sorted(dictionary.items(), key=lambda x: x[1], reverse=True)
    sorted_dictionary = dict(sorted_list)
    return sorted_dictionary