Return the translation object of an specific field in a Translatable
        istance

        @type lang: string
        @param lang: a string with the name of the language

        @type field: string
        @param field: a string with the name that we try to get

        @rtype: Translation
        @return: Returns a translation object

def get_translation_obj(self, lang, field, create=False):
        """
        Return the translation object of an specific field in a Translatable
        istance

        @type lang: string
        @param lang: a string with the name of the language

        @type field: string
        @param field: a string with the name that we try to get

        @rtype: Translation
        @return: Returns a translation object
        """
        trans = None
        try:
            trans = Translation.objects.get(
                object_id=self.id,
                content_type=ContentType.objects.get_for_model(self),
                lang=lang,
                field=field,
            )
        except Translation.DoesNotExist:
            if create:
                trans = Translation.objects.create(
                    object_id=self.id,
                    content_type=ContentType.objects.get_for_model(self),
                    lang=lang,
                    field=field,
                )
        return trans