What is [Meta-Enter] in a WSL2 Ubuntu window on Win10 please?

examples/prompts/mouse-support.py prints out that it requires [Meta-Enter] or [Esc] followed by [Enter] to close the multiline but I do not know what [Meta-Enter] is on the keyboard and [Esc] [Enter] does not do it. I have to use [Ctrl-C] to exit the script which of course bypasses the final print in the example.

Same behavior in a Win10 CMD.EXE window under python 3.9.5.

What is [Meta-Enter] on a WIn10 system in a WSL2 Ubuntu window?

It isn't Alt-Enter, which on stock Win10 just makes the window full-screen, and Ctrl-Enter just goes to a new line in the multiline.

TIA for any help you can offer.

Environment:
OS: Win10, WSL2, Linux [my system name] 4.4.0-19041-Microsoft #488-Microsoft Mon Sep 01 13:43:00 PST 2020 x86_64 x86_64 x86_64 GNU/Linux
Python: Python 3.8.10 (default, Jun 2 2021, 10:49:15)

Newly installed prompt-toolkit V3.0.19 in pipenv virtual environment

Peter

Start with examples/prompts/mouse-support.py and reproduce the multiline exit behavior in the reported WSL2 Ubuntu or Windows CMD environment. Check how the example describes its key bindings and document what [Meta-Enter] means on these systems; done means the instructions are understandable and the documented alternative works.