https://docs.python.org/3/library/idle.html
IDLE is Python’s Integrated Development and Learning Environment.
It is coded in 100% pure Python, using the tkinter GUI toolkit.
IDLE is cross-platform: works mostly the same on Windows, Unix, and MacOS.
It has an interactive interpreter, a multi-window text editor, a debugger.
IDLE has two main window types, the Shell window and the Editor window.
Debian packages: idle, idle-python2.7, idle-python3.7.