input: Write a function to compute the sum of the values of a given dictionary. The function should take a dictionary as input, iterate over all key-value pairs, accumulate the values, and return the total sum of the values. If the dictionary is empty, the function should return 0.
  
  assert dict_sum({'A':5, 'B':6, 'C':10})==21
  assert dict_sum({})==0
  assert dict_sum({'X':1, 'Y':2, 'Z':3})==6
output: def dict_sum(d):
      return sum(d.values())