Installing coremltools on MacOS

After watching ML Core in Depth (one of WWDC 2017 video), I have decided to try coremltools on my MacBook Pro (MacOS Sierra, Version 10.12.4). 

When I type,

 # pip install coremltools

it fails with the following error message:

Could not find a version that satisfies the requirement coremltools (from versions: )
No matching distribution found for coremltools

This is because Python on my MacOS is 3.5.2, while coremltools requires 2.7. 

To solve this problem, I have installed virtualenv by typing

 # pip install virtualenv

which will install vittualenv (globally). 

Then, I created a virtual environment "py27" with following command

 # virtualenv --python=/usr/bin/python2.7 py27

where py27 is the name of directory (to hold this environment). 

Once this environment is created, I can activate it by typing

 # source py27/bin/activate

You can verify it by typing

 (p27)# python --version
 Python 2.7.10

Now you are ready to install coremltools by typing

 (p27)# pip install -U coremltools

By the way, you can exit from this virtual environment by typing

 (p27)# deactivate