Install pip on macOS

Run next command.

sudo easy_install pip

Solve problem double click not working on macOS High Sierra

In short this problem occur from double click speed.
Go to "Accessibility" in System Preference.
Down double click speed to half value in Mouse & Trackpad.
I can't understand why that value was maximum as default.

Get screenshot without drop shadow on macOS High Sierra

Press the next keys.

CMD + SHIFT + 4

And press space key.
You can see capture frame for getting screenshot of specific windows.
Now, click left mouse on the capture frame with press hold ALT key.
Then you can get screenshot without drop shadow like next picture.