@classmethod decorators not being properly treated #499

Environment data

VS Code version: 1.19.0
Python Extension version:
Python Version: 3.6
OS and version: osx 10.13

I have a class defined as below

class A(object):
  @classmethod
  def load(cls, pk):
    pass
a = A()

Actual behavior

When I type a.load, cls is still expected as the first argument.

Expected behavior

I would expect that pk would be expected as the first argument.

Steps to reproduce:

Type the above

Logs

Not really applicable I wouldn't think.

I don't expect every decorator to be handled perfectly, but I would think that @classmethod is common enough that it should be handled properly.