input: Write a python function to merge two dictionaries.
  assert merge_dicts({'a': 1, 'b': 2}, {'b': 3, 'c': 4}) == {'a': 1, 'b': 3, 'c': 4}
  assert merge_dicts({'key1': 'value1'}, {'key2': 'value2'}) == {'key1': 'value1', 'key2': 'value2'}
  assert merge_dicts({}, {'new_key': 'new_value'}) == {'new_key': 'new_value'}
output: def merge_dicts(dict1, dict2):
      result = dict1.copy()
      result.update(dict2)
      return result