input: Write a function to take in a dictionary (string → integer) and return the sum of all values in the dictionary. If the dictionary is empty then return 0.
  
  assert compute_dict_sum({"a": 5, "b": 10, "c": 15}) == 30
  assert compute_dict_sum({"x": 1, "y": 2}) == 3
  assert compute_dict_sum({}) == 0
output: def compute_dict_sum(d):
      return sum(d.values())