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