input: Write a function to sort a dictionary by its keys.
  assert sort_dictionary_by_keys({"name": "John", "age": 24, "class": "Engineering"}) == [("age", 24), ("class", "Engineering"), ("name", "John")]
  assert sort_dictionary_by_keys({"b": 2, "a": 1, "c": 3}) == [("a", 1), ("b", 2), ("c", 3)]
  assert sort_dictionary_by_keys({"three": 3, "one": 1, "two": 2}) == [("one", 1), ("three", 3), ("two", 2)]
output: def sort_dictionary_by_keys(d):
      return sorted(d.items())