How to use the mnemonic.mn_encode function in mnemonic

def get_mnemonic(seed):
    return ' '.join(mnemonic.mn_encode(seed))

elif cmd2 == 'history':
            print "show the transaction history"
        elif cmd2 == 'label':
            print "assign a label to an item"
        elif cmd2 == 'gui':
            print "start the GUI"
        elif cmd2 == 'mktx':
            print "create a signed transaction. password protected"
            print "syntax: mktx   [label]"
        elif cmd2 == 'seed':
            print "show generation seed of your wallet. password protected."

    elif cmd == 'seed':
        import mnemonic
        seed = wallet.pw_decode( wallet.seed, password)
        print seed, '"'+' '.join(mnemonic.mn_encode(seed))+'"'

    elif cmd == 'validateaddress':
        addr = args[1]
        print wallet.is_valid(addr)

    elif cmd == 'balance':
        try:
            addrs = args[1:]
        except:
            pass
        if addrs == []:
            c, u = wallet.get_balance()
            if u:
                print c*1e-8, u*1e-8
            else:
                print c*1e-8

return
        else:
            password = None
            
        try:
            seed = wallet.pw_decode(wallet.seed, password)
        except:
            QMessageBox.warning(parent, _('Error'),
                                _('Incorrect Password'), _('OK'))
            return

        dialog = QDialog(None)
        dialog.setModal(1)
        dialog.setWindowTitle(_("Seed"))

        brainwallet = ' '.join(mnemonic.mn_encode(seed))

        msg = _('<p>"%s"</p>'
                "<p>If you memorise or write down these 12 words, you will always be able to recover your wallet.</p>"
                "<p>This is called a 'BrainWallet'. The order of words is important. Case does not matter (capitals or lowercase).</p>") % brainwallet
        main_text = QLabel(msg)
        main_text.setWordWrap(True)

        logo = QLabel()
        logo.setPixmap(QPixmap(":icons/seed.png").scaledToWidth(56))

        if parent:
            app = parent.app
        else:
            app = QApplication

        copy_function = lambda: app.clipboard().setText(brainwallet)

# Count number of hex digits for informational purposes
    if len(hex_seed) != len(seed):
        hex_digit_count = 0
        for h in seed:
            if '0' <= h <= '9' or 'a' <= h <= 'f':
                hex_digit_count += 1
        warn('info: {} out of {} characters in decrypted seed are lowercase hex digits'
             .format(hex_digit_count, len(seed)))

    if len(hex_seed) < 8:
        warn('length of valid hex-encoded digits is less than 8, giving up')
        return seed, None
    else:
        if len(hex_seed) % 8 != 0:
            warn('length of hex-encoded digits is not divisible by 8, some digits will not be included in the mnemonic')
        return seed, ' '.join(mnemonic.mn_encode(hex_seed))