input: Write a function to compute the sum of the values of a given dictionary. The function should iterate over the dictionary items, add up all the values, and return the total sum. If the dictionary is empty, it should return 0.
  
  assert dict_sum({'A': 5, 'B': 6, 'C': 10})==21
  assert dict_sum({})==0
output: def dict_sum(d):
      return sum(d.values())