Are you sure it can be missing? I tried to delete the start function from an Idle handle and here is what I got:

~~~~~~
>>> import pyuv
>>>
>>> l = pyuv.Loop()
>>> i = pyuv.Idle(l)
>>> del i.start
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'pyuv.Idle' object attribute 'start' is read-only
>>>
~~~~~~