how to transition to python 3 in terminal code example

Example 1: mac why is python installed in usr and application

$ pyenv global 3.7.3
# and verify it worked 
$ pyenv version
3.7.3 (set by /Users/mbbroberg/.pyenv/version)

Example 2: mac catallina python3

$ brew install pyenv

Example 3: transition from python 2 to 3 terminal

alias python="python3"