How to install pyserial & tkinter on macOS High Sierra with python 2.7.10 HD

In this installation tutorial, I explained how to install pySerial and Tcl/Tk on the new macOS High Sierra - Version 10.13.4 with the built-in Python 2.7.10. These two modules can for example allow the development of an arduino microcontroller-based python program with graphical user interface (GUI) provided by Tk (Tkinter) and the python/arduino communication via usb serial port thanks to pyserial. Comments: Tcl/Tk 8.5 is normally linked to python 2.7. It was reported that 8.5.9 has 2 serious bugs. I then decided to install the 8.5.18.0 as Mac Disk Image (DMG) which is recommended for macOS 10.5 (leopard) as you can see on the following link: https://www.activestate.com/activetcl/downloads pySerial was installed from code source on: https://pypi.python.org/pypi/pyserial/2.7