python question

Given dictionaries, d1 and d2, create a new dictionary, d3, with the following properties: For each key:value pair a:b in d1, if a is not a key of d2 then add a:b to the new dictionary. For each key:value pair a:b in d2, if a is not a key of d1 then add a:b to the new dictionary. For example, when d 1 is { 2 : 3 , 8 : 19, 6 : 4, 5 : 12) and d2 is {2: 5 , 4 : 3 ' 3 : 9, your code should produce this