tmux (source code) is a terminal multiplexer implementation often used during Python development on Linux and macOS. tmux grants greater control over a programmers's development environment by making it easier to use many shells at once and attaching to both local and remote shell sessions.
Tmux and Vim - even better together explains how using tmux with the Vim editor provide better multi-window navigation using only keystrokes and other benefits. As an avid tmux+Vim user myself, I can attest to how great these two tools complement each other.
There are a slew of "cheat sheets" for tmux out there, here are a few good ones: