confusion about __getattr__

[Russ Cox]

Could someone explain the error message in the
following to me?  I apologize if it should be
obvious, but clearly I have the wrong mental
picture of what's going on.  

g% python
Python 2.2+ (#0, Jan 16 2002, 19:28:19) [C] on unknown
Type "help", "copyright", "credits" or "license" for more information.
>>> class Test:
... 	def __getattr__(self, name):
... 		return '__getattr__ for '+name
... 	def __init__(self):
... 		self.foo = 'bar'
... 	def asdf(self):
... 		return 'jkl;'
... 
>>> t=Test()
>>> t.foo
'bar'
>>> t.sdfsdfdsf
'__getattr__ for sdfsdfdsf'
>>> t.asdf()
'jkl;'
>>> t.asdf
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: 'str' object is not callable
>>> 

What is the str object in question that isn't callable?

Thanks.
Russ