input: Write a python function to sort a dictionary by its keys.
  assert sortDict({'Tom': 20, 'Jerry': 30, 'Jose': 25}) == {'Jerry': 30, 'Jose': 25, 'Tom': 20}
  assert sortDict({'banana': 3, 'apple': 4, 'pear': 1, 'orange': 2}) == {'apple': 4, 'banana': 3, 'orange': 2, 'pear': 1}
  assert sortDict({'d': 4, 'a': 1, 'b': 2, 'c': 3}) == {'a': 1, 'b': 2, 'c': 3, 'd': 4}
output: def sortDict(d):
      return dict(sorted(d.items()))