input: Write a function to compute the sum of all values in a given dictionary where the dictionary keys are strings and the values are integers. If the dictionary is empty, return 0.
  assert compute_dict_sum({"a": 5, "b": 10, "c": 15})==30
  assert compute_dict_sum({"x": 2, "y": 4})==6
  assert compute_dict_sum({})==0
  assert compute_dict_sum({"key1": 1, "key2": -1, "key3": 3})==3
output: def compute_dict_sum(d):
      return sum(d.values()) if d else 0