>>> from sklearn import tree
>>> X = [[0, 0], [1, 1]]
>>> Y = [0, 1]
>>> clf = tree.DecisionTreeClassifier()
>>> clf = clf.fit(X, Y)

class sklearn.tree.DecisionTreeClassifier(criterion=’gini’, splitter=’best’, max_depth=None, min_samples_split=2,
                                          min_samples_leaf=1, min_weight_fraction_leaf=0.0, max_features=None, 
                                          random_state=None, max_leaf_nodes=None, min_impurity_decrease=0.0,
                                           min_impurity_split=None, class_weight=None, presort=False)

>>> clf.predict([[2., 2.]])
array([1])