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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def set_timezone(rollback=False):
 """ Set the time zone on the server using Django settings.TIME_ZONE """

    if not rollback:
        if contains(filename='/etc/timezone', text=env.TIME_ZONE, use_sudo=True):
            return False
        if env.verbosity:
            print env.host, "CHANGING TIMEZONE /etc/timezone to "+env.TIME_ZONE
        _backup_file('/etc/timezone')
        sudo('echo %s > /tmp/timezone'% env.TIME_ZONE)
        sudo('cp -f /tmp/timezone /etc/timezone')
        sudo('dpkg-reconfigure --frontend noninteractive tzdata')
    else:
        _restore_fie('/etc/timezone')
        sudo('dpkg-reconfigure --frontend noninteractive tzdata')
    return True