human
Solve the following python programming problem given the following code:
def replace_nan(trainingset, replace_with = None) : 
    '
    Replace instanced of "not a number" with either the mean of the signal feature
    or a specific value assigned by `replace_with`
    ' 
    training_data = np.array ([instance.features for instance in trainingset]).astype (np.float64) 
    def encoder(dataset) : 
        manipulated_dataset = copy.deepcopy (dataset) 
        for instance in manipulated_dataset : 
            instance.features = instance.features.astype (np.float64) 
            if np.sum (np.isnan (instance.features)) : 
                if (replace_with == None) : 
                    instance.features [np.isnan (instance.features)] = means [np.isnan (instance.features)] 
else : 
                    instance.features [np.isnan (instance.features)] = replace_with 
return manipulated_dataset 
if (replace_with == None) : 
        means = np.mean (np.nan_to_num (replace_with), axis = 0) 
return encoder 

    
    

    Fix the buggy line: means = np.mean (np.nan_to_num (replace_with), axis = 0)
assistant
#Here is Python program to fix the buggy line: means = np.

means = np.mean (np.nan_to_num (training_data), axis = 0)