cannot import name 'normalize' from 'keras.utils'について

1.前提・実現したいこと
cannot import name 'normalize' from 'keras.utils'についての対処方法
が知りたい。

2.発生している問題・エラーメッセージ

ImportError Traceback (most recent call last)
<ipython-input-21-03ab5b75dc12> in <module>()
1 from keras.datasets import boston_housing
----> 2 from keras.utils import normalize
3
4 def min_max(x, axis=None, min_val=False, max_val=False):
5 if type(min_val)==bool:

ImportError: cannot import name 'normalize' from 'keras.utils' (/usr/local/lib/python3.7/dist-packages/keras/utils/init.py)

3.該当のソースコード

python３
1from keras.datasets import boston_housing
2from keras.utils import normalize
3
4def min_max(x, axis=None, min_val=False, max_val=False):
5  if type(min_val)==bool:
6    min_val = x.min(axis=axis, keepdims=True)
7  if type(max_val)==bool:
8    max_val = x.max(axis=axis, keepdims=True)
9  result = (x-min_val)/(max_val-min_val)
10  return result, min_val, max_val
11
12(x_train, y_train), (x_test, y_test) = boston_housing.load_data()
13
14print(x_train.shape,x_test.shape)
15print(y_train.shape,y_test.shape)
16
17#0-1正規化
18x_train, x_min, x_max = min_max(x_train, axis=0)
19y_train, y_min, y_max = min_max(y_train, axis=0)
20#学習データのレンジで。y_minとy_maxは後で使う。
21x_test, _, _,=min_max(x_test, axis=0, min_val=x_min, max_val=x_max)
22y_test, _, _,=min_max(y_test, axis=0, min_val=y_min, max_val=y_max)