input: 
  def evaluate_model_accuracy(clf, X_train, y_train, X_test, y_test):
      """Evaluate the accuracy of a given machine-learning model using sklearn's accuracy_score.
      >>> evaluate_model_accuracy(SVC(kernel='poly', degree=2, gamma=0.05), X_train, y_train, X_test, y_test)
      "Accuracy: 0.92"
      """
      clf.fit(X_train, y_train)
      y_pred = clf.predict(X_test)
      accuracy = accuracy_score(y_test, y_pred)
      return "Accuracy: " + str(accuracy)
  
output:     from sklearn.metrics import accuracy_score