input: Write a function to compute the sum of the values of a given dictionary. The function should take a dictionary as input and return the sum of all its values.
  def dict_sum(dictionary):
      sum = 0
      for key, value in dictionary.items():
          sum += value
      return sum
  assert dict_sum({'A':5, 'B':6, 'C':10})==21
  assert dict_sum({'X':1, 'Y':2, 'Z':3})==6
  assert dict_sum({})==0
  assert dict_sum({'One':10, 'Two':20, 'Three':30})==60
output: def dict_sum(dictionary):
      sum = 0
      for key, value in dictionary.items():
          sum += value
      return sum