Added typecheck where self.__dict__ is used.

[choni]

It's about #381 .
To avoid error when self.dict contains something not function.

[okuta]

Thank you for your PR.

isinstance returns true in the case of subclass.
And, FunctionSet may contain FunctionSet.
Therefore, isinstance(func, (function.Function, function.FunctionSet)) is better.

Chainer project uses PEP8 and a part of OpenStack Style Guidelines related to general coding style.
http://docs.chainer.org/en/stable/contribution.html#coding-guidelines
Please fix coding style.

[choni]

OK. Fixed.

[choni]

Fixed typecheck in _get_sorted_funcs.
Because, When _get_sorted_funcs is called dict not contains functions but tuples like below.

('conv1b', <chainer.functions.convolution_2d.Convolution2D object at 0x7fc5a47295d0>)

[okuta]

I think to be good to use six.itervalues.

[choni]

I overlooked iteritems is used in _get_sorted_funcs, instead of itervalues is used in to_gpu and to_cpu.
About _get_sorted_funcs, iteritems is used for sorted function.
So, I think dict.values() is not suitable.
And, I simplified if clause of _get_sorted_funcs.

[okuta]

OK. I misunderstood.

[okuta]

LGTM!
Thank you.