I have Drush 10.3.2-dev working on my system but I also need to work on an old project in Drupal 7, so I need Drush 7 to work on that particular project.
I downloaded Drush 7, unpacked it in a folder, drush
script is executable, but when I try to use it with ./drush
I get
Unable to load autoload.php. Drush now requires Composer in order to install its dependencies and autoload classes. Please see README.md
How can I use old Drush that is compatible with Drupal 7 in parallel with the newer version?