Corte de control

with open('movimientos.txt', 'rt') as movs:
    linea = movs.readline()
    nro_cta, importe = linea.rstrip().split(',') if linea else ('', '')
    print (nro_cta, importe)
    total = 0

    while linea:
        cta_ant = nro_cta
        tot_cta = 0
        print ('cta',cta_ant)
        print ('importe',importe)

        while linea and nro_cta == cta_ant:
            print (importe)
            tot_cta += int(importe)
            print (nro_cta, importe)
            linea = movs.readline()
            nro_cta, importe = linea.rstrip().split(',') if linea else ('', '')

        print ('cierre')
        print ('El total de la cuenta {} es {}:'.format(cta_ant, tot_cta))
        total += tot_cta

print ('Total Gral:', total)