Install Python3 and use with SublimeText3 for MacOS

Install Homebrew
1. xcode-select --install
2. ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
3. brew doctor

Install Python3 using Homebrew
1. brew install python3

Install packages for Python3
1. pip3 install [package name without brackets]

Using Python3 as a Build System in SublimeText3
1. Select: Tools -> Build System -> New Build System 
2. Replace default text with lines below:
{
    "cmd": ["python3", "-i", "-u", "$file"],
    "file_regex": "^[ ]File \"(...?)\", line ([0-9]*)",
    "selector": "source.python"
}
3. Save the file as: python3.sublime-build
4. To run .py files with python 3, select Tools -> Build system -> python3