Installation ESP8266 Python3 Error : The problem is that the symlink for python3 is incorrect. To correct it:
$ cd /Users/[your-username]/Library/Arduino15/packages/esp8266/tools/python3/3.7.2-post1/
$ rm python3
$ which python3
$ ln -s [path-returned-by-the-above-command] python3
The pinout on the connector side are inverted !!!!