Gaussian_NB' object has no attribute 'prior_prob'

This error message means that the "prior_prob" attribute is not defined for the "Gaussian_NB" object.

Possible reasons for this error include:

1. The "prior_prob" attribute was not defined in the "Gaussian_NB" class or was deleted from the object.
2. The "prior_prob" attribute was misspelled or named differently.
3. The "prior_prob" attribute is defined in a parent class or a superclass, but not in the "Gaussian_NB" subclass.

To fix this error, you need to check the code that defines the "Gaussian_NB" object and make sure that the "prior_prob" attribute is defined correctly. You can also check the documentation or examples of the "Gaussian_NB" class to see how the "prior_prob" should be defined and used.