cannot import name ‘imputer’ from ‘sklearn.preprocessing’

from sklearn.impute import SimpleImputer 
imputer = SimpleImputer(missing_values=np.nan, strategy='mean')

Here is what the above code is Doing:
1. Creating an object of the class SimpleImputer.
2. Passing the parameters missing_values and strategy to the constructor.
3. Creating an object of the class SimpleImputer.
4. Passing the parameters missing_values and strategy to the constructor.
5. Fitting the imputer object to the training data.
6. Transforming the training data by replacing missing values with the mean of the column.
7. Transforming the testing data by replacing missing values with the mean of the column.