Created originally on Bitbucket by vaibhavsood12 (Vaibhav Sood)
Changesets for this Pull Request have not been imported, because it had been already declined on Bitbucket. Marked as closed by the import user.
Addressed the review comment from Amaury from pull request #337 (closed). Added the CHECKTYPES condition to match the CPython code
Also improved the test cases to test mixed types and the reverse (wrap_binaryfunc_r) function
Apologies for creating this additional pull request (probably should have combined #345 (closed) and this one)