No, there is not any library function for Root mean square error (RMSE) in python, but you can use the library Scikit Learn for machine learning and it can be easily employed by using Python language. It has the function for Mean Squared Error.
The function is named as mean_squared_error which I am mentioning below, where y_true would be real class values for the data tuples and y_pred would be the predicted values, predicted by the machine learning algorithm you are using.
The mean_squared_error(y_true, y_pred) function:-
You have to modify this function to get RMSE (by using sqrt function using Python).
See the code below:-
from sklearn.metrics import mean_squared_error
from math import sqrt
RMSD = sqrt(mean_squared_error(testing_y, prediction))