input: from typing import Tuple
  
  def evaluate_ml_model(clf, X_train, y_train, X_test, y_test) -> Tuple[float, str]:
      """Evaluates the accuracy of a machine-learning model.
      >>> from sklearn.svm import SVC
      >>> clf = SVC(kernel='poly', degree=2, gamma=0.05)
      >>> X_train, y_train, X_test, y_test = ...
      >>> evaluate_ml_model(clf, X_train, y_train, X_test, y_test)
      (0.85, "Accuracy: 0.85")
      """
output:     clf.fit(X_train, y_train)
      accuracy = clf.score(X_test, y_test)
      return accuracy, f"Accuracy: {accuracy:.2f}"