Add _set_fitted_parameters method to NullTransformer

[frances-h]

Problem Description

We'd like to be able to get a transformer into a fitted state using known parameters instead of existing data. This would allow us to set up a transformer to be able to reverse transform without first having to fit it on real data.

Expected behavior

Add the method _set_fitted_parameters to the NullTransformer. When called, the provided arguments should be set on the transformer to get it into a 'fitted' state so that it can be used to reverse transform. After being called, a user should be able to call reverse_transform and have it work as expected.

def _set_fitted_parameters(self, null_percentage):

• Args:
  • null_percentage [float]: The percentage of values that should be replaced with null values. Should be used to set self._null_percentage

This method should not return anything.