Python Class & Methods definition error with attributes - Request for Code Review

I'm not an expert in Python and I'm not getting this to work. It is for a coding challenge to enter a new course, let's say 'academic purpose'

class ClaseVehiculo:
        def __init__(self,tipo,color):
            self.tipo = tipo
            self.color = color 
            self.velocidad = 0
            if not ( tipo in ['auto','camioneta','moto']) :
               print ( 'Tipo de vehiculo no reconocido. No se puede crear la clase: ClaseVehiculo.' )
               CANCEL
        @classmethod
        def Acelerar(self,variacion):
            self.velocidad += variacion
            if self.velocidad < 0:
                self.velocidad = 0
            if self.velocidad > 100:
                self.velocidad = 100
    return ClaseVehiculo

a = ClaseVehiculo('auto','verde')
print ( a )
print ( a.tipo() ) 

Apparently, 'a' is initialized as a ClaseVehiculo class but

when Print (a.tipo() ) 'tipo' is not recognized as a class attribute