setting “python_requires” with ">=3.5" is a better way to declare Python compatibility

[PyVCEchecker]

I noticed such a declaration in README

"It depends on pySerial and is compatible with Python 3.5 and later."

I guess you want to set python>=3.5. But I think it is a better way to declare Python compatibility by using the keyword argument python_requires for some reasons:

• Descriptions in python_requires will be reflected in the metadata
• “pip install” can check such metadata on the fly during distribution selection , and prevent from downloading and installing the incompatible package versions.
• If the user does not specify any version constraint, pip can automatically choose the latest compatible package version for users.

Way to improve:
modify setup() in setup.py, add python_requires keyword argument:

setup(…
     python_requires=">=3.5",
     …)

Thanks for your attention.
Best regrads,
PyVCEchecker