I have replied on SO, but I thought I would also reply here with more details to help you out 
As you have discovered, dictionaries in python will raise a KeyError when you try to access the value for a key that doesnât exist in the dictionary. But dictionaries have a built in method called get, which lets you specify a default for when the key doesnât exist. This avoids the need to first check if key in dict: etc. 


