关于深度学习决策树模型的问题

Question

想用决策树模型分类数据，但是总报一些奇奇怪怪的错

import pandas as pd
data = pd.read_csv("dataset.csv")
#%%
data.head()
#%%
data.Disease.value_counts()
#%%
data.describe()
#%%
feature = data[['Symptom_1', 'Symptom_2', 'Symptom_3']]
target = data[['Disease']]
#%%
from sklearn import tree
model = tree.DecisionTreeClassifier()
model = model.fit(feature,target)
#%%
import graphviz
dot_data = tree.export_graphviz(model,out_file=None)
graph = graphviz.Source(dot_data)
graph.render("disease_decision_tree")

NameError                                 Traceback (most recent call last)
Input In [16], in <module>
      1 import graphviz
----> 2 dot_data = tree.export_graphviz(model,out_file=None)
      3 graph = graphviz.Source(dot_data)
      4 graph.render("disease_decision_tree")

NameError: name 'tree' is not defined