You are given a dictionary d whose values are all numbers.
Modify d in place by adding a new key 'total' whose value is the sum of all the values already in d (computed before the new key is added).
If d is empty, the sum is 0, so 'total' becomes 0.
Return None.
NOTE: This is a function-type question — you only write the function. Do not read input or print anything; a hidden checker calls your function and checks its return value.
Arguments
{'a': 1, 'b': 2, 'c': 3}
Returns
{'a': 1, 'b': 2, 'c': 3, 'total': 6}