@Larry Hasting: If  you check my patch, it's the case where I modify the 
documentation and add a DeprecationWarning in the code.

@Yury Selivanov, @Nick Coghlan, @Brett Cannon: From your point of views, 
I need to propose a patch just for the documentation, I agree with that.

@Brett Cannon: In the current patch, I implemented a test with the 
python version. If the version is greater or equal than 3.7, in this 
case, I raise an exception.

I propose to follow the solution of @Yury Selinanov, just deprecate the 
function in the documentation and keep the check in the unit test for 
the version.

Are you agree?

Thanks