<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def default_ubuntu_tr(mod):
 """ Default translation function for Ubuntu based systems """

    pkg = 'python-%s' % mod.lower()
    py2pkg = pkg
    py3pkg = 'python3-%s' % mod.lower()
    return (pkg, py2pkg, py3pkg)