input: Write a function `merge_dict` that takes two dictionaries `dict_a` and `dict_b` as input and merges them into a single dictionary. The function should return the merged dictionary.
  
  
  def merge_dict(dict_a, dict_b):
      merged_dict = {**dict_a, **dict_b}
      return merged_dict
  
  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':30, 'z':40}) == {'x':10, 'y':30, 'z':40}
  assert merge_dict({}, {'p':1, 'q':2}) == {'p':1, 'q':2}
  assert merge_dict({'m':0, 'n':0}, {}) == {'m':0, 'n':0}
  assert merge_dict({}, {}) == {}
  
output: def merge_dict(dict_a, dict_b):
      merged_dict = {**dict_a, **dict_b}
      return merged_dict