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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def ca_bundle(self, ca_bundle):
 """ Sets the ca_bundle of this V1alpha1WebhookClientConfig. `caBundle` is a PEM encoded CA bundle which will be used to validate the webhook's server certificate. If unspecified, system trust roots on the apiserver are used. :param ca_bundle: The ca_bundle of this V1alpha1WebhookClientConfig. :type: str """

        if ca_bundle is not None and not re.search('^(?:[A-Za-z0-9+\/]{4})*(?:[A-Za-z0-9+\/]{2}==|[A-Za-z0-9+\/]{3}=)?$', ca_bundle):
            raise ValueError("Invalid value for `ca_bundle`, must be a follow pattern or equal to `/^(?:[A-Za-z0-9+\/]{4})*(?:[A-Za-z0-9+\/]{2}==|[A-Za-z0-9+\/]{3}=)?$/`")

        self._ca_bundle = ca_bundle