This patch fixed the problem which can be best demonstrated with the following snippet:

>>> import ivi
>>> a = ivi.agilent.agilentE4435B()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/<...>/ivi/agilent/agilentE4435B.py", line 35, in __init__
    super(agilentE4434B, self).__init__(*args, **kwargs)
NameError: name 'agilentE4434B' is not defined

That seems to be the same issue as #8 and #55. Copy & paste is a dangerous development methodology, isn't it a good idea to replace all the wrapper classed with something saner or at least add a unit test to ensure that all devices can default construct?