$ python procesador.py
Traceback (most recent call last):
  File "procesador.py", line 24, in <module>
    resultado = total_ventas_por_mes("ventas.csv")
                ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
  File "procesador.py", line 19, in total_ventas_por_mes
    totales[mes] = totales.get(mes, 0) + precio
                   ~~~~~~~~~~~~~~~~~~~~^~~~~~~~
TypeError: unsupported operand type(s) for +: 'int' and 'str'