py3clean: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/py3clean - from package: python3-minimal

You may install the required package with command apt-get install {package}
Error in other languages:
py3clean: bevel nie gevind nie
py3clean: comandă negăsită
py3clean: comando não encontrado
py3clean: commande introuvable
py3clean: command not found
py3clean: käsku ei ole
py3clean: không tìm thấy lệnh
py3clean: komanda nerasta
py3clean: Kommando nicht gefunden.
py3clean: kommandot finns inte
py3clean: komut yok
py3clean: nie znaleziono polecenia
py3clean: níor aimsíodh an t-ordú
py3clean: no se encontró la orden
py3clean: no s'ha trobat l'ordre
py3clean: opdracht niet gevonden
py3clean: parancs nem található
py3clean: perintah tidak ditemukan
py3clean: príkaz nenájdený
py3clean: příkaz nenalezen
py3clean: команда не найдена
py3clean: командата не е открита
py3clean: 命令找不到
py3clean: コマンドが見つかりません