[arch-general] python 3.5 with or without python 3.7

[Pascal via arch-general]

hello members (and happy new year),
my system is up to date and works with python 3.7.
for a specific need, I want to install python 3.5 but cannot go down
because its installation breaks an dependency: :: installing python
(3.5.2-1) breaks dependency 'python>=3.7' required by libreoffice-still.
what do you think is the easiest way to achieve my goals ?
regards, lacsaP.