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. Function should return the merged 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({'one':1}, {'two':2})=={'one':1, 'two':2}
  assert merge_dict({}, {'empty':0})=={'empty':0}
  assert merge_dict({'key': 'value'}, {})=={'key': 'value'}
output: def merge_dict(dict1, dict2):
      merged = dict1.copy()
      merged.update(dict2)
      return merged