input: Write a function to predict the class labels of a given set of data using a DecisionTreeClassifier trained on a dataset with features: Length, Width, Height, and Weight. The function should return the predicted label for the provided data.  
  assert predict([1, 2, 3, 4])==1  
  assert predict([2, 4, 6, 8])==2  
  assert predict([3, 6, 9, 12])==3
output: def predict(data):
      from sklearn.tree import DecisionTreeClassifier
      X_train = [[1, 2, 3, 4], [2, 4, 6, 8], [3, 6, 9, 12]]
      y_train = [1, 2, 3]
      clf = DecisionTreeClassifier()
      clf.fit(X_train, y_train)
      return clf.predict([data])[0]