input: Write a function to combine two dictionaries of similar structure together, such that the entries in the two dictionaries are merged into a single dictionary.
  assert merge_dict({'a':1, 'b':2, 'c':3}, {'d':4, 'e':5, 'f':6})=={'a':1, 'b':2, 'c':3, 'd':4, 'e':5, 'f':6}
  assert merge_dict({'x': 10, 'y': 20}, {'y': 25, 'z': 30})=={'x': 10, 'y': 25, 'z': 30}
  assert merge_dict({}, {'g': 7, 'h': 8})=={'g': 7, 'h': 8}
  assert merge_dict({'i': 9}, {})=={'i': 9}
  assert merge_dict({}, {})=={}
output: def merge_dict(dict1, dict2):
      result = dict1.copy()
      result.update(dict2)
      return result