make python 3 default code example

Example 1: how to set default python version in macos

ln -s -f /usr/local/bin/python3.7 /usr/local/bin/python

Example 2: set python3 as default mac

# it is said not to do but I used it anyway, because of the conveniency
$ echo "alias python=/usr/local/bin/python3.7" >> ~/.zshrc

Example 3: mac catallina python3

$ brew install pyenv

Example 4: use python as python3 zsh

# Go into your .zshrc file. Is there a line that reads:
alias python='python3'

Example 5: update link python is python 3

$ unalias python
$ python --version
Python 2.7.6