python - dict.get() - default arg evaluated even upon success

Question

Why is the default in dict.get(key[, default]) evaluated even if the key is in the dictionary?

>>> key = 'foo'
>>> a={}
>>> b={key:'bar'}
>>> b.get(key, a[key])
Traceback (most recent call last):
  File "<pyshell#5>", line 1, in <module>
    b.get(key, a[key])
KeyError: 'foo'

Answer 1

As in any function call, the arguments are evaluated before the call is executed.
In this case dict.get() is no exception...