input: Write a function to merge two dictionaries of similar structure together, such that the entries in the two dictionaries are merged into a single dictionary. Return the combined 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}, {'z':30})=={'x':10, 'y':20, 'z':30}
  assert merge_dict({}, {'p':100, 'q':200})=={'p':100, 'q':200}
  assert merge_dict({'k':5, 'm':7}, {})=={'k':5, 'm':7}
  assert merge_dict({}, {})=={}
output: def merge_dict(dict1, dict2):
      combined = dict1.copy()
      combined.update(dict2)
      return combined