This is what I came across with Intellij 2017.3.4, where he could find every module except sys and time in the editor, but everything will work fine. I had version 2.4 and 3.5 for python, and it didn't seem to be what I chose as the SDK. I tried to add and remove them.
When I went to Project Structure -> Platform Settings -> SDKs -> Python 3.5 -> Packages, he requested a warning that Python packaging tools not found. and had an install link. I installed it, and the editor no longer complained about time and time. When I switched the SDK to 2.7 (without installing packing tools), he again complained.
So, I'm not quite sure what is going on, which seemed to fix it for me, that other people are facing this problem.
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