input: 
  from sklearn.naive_bayes import GaussianNB
  
  def classify_emails(X_train, y_train, X_test):
      """Construct a naive bayes classifier to classify emails as spam or not spam.
      >>> model = classify_emails([[1, 2], [2, 3], [3, 4]], [0, 1, 1], [[1, 1], [4, 4]])
      >>> print(model)
      [0 1]
      """
      # Create a Gaussian Classifier
      model = GaussianNB()
      
      # Train the model using the training sets 
      model.fit(X_train, y_train)
      
      # Predict Output 
      y_pred = model.predict(X_test)
      
      return y_pred
  
output:     return y_pred