diff --git a/02. python essentials/02.07 mutable and immutable data types.ipynb.REMOVED.git-id b/02. python essentials/02.07 mutable and immutable data types.ipynb.REMOVED.git-id
index 1c948887..8209eddf 100644
--- a/02. python essentials/02.07 mutable and immutable data types.ipynb.REMOVED.git-id	
+++ b/02. python essentials/02.07 mutable and immutable data types.ipynb.REMOVED.git-id	
@@ -1 +1 @@
-a1ec3798790928d60f2fd7eb95e63eadc9a2ddee
\ No newline at end of file
+cc103892979790d019e34c703f9bdbc6438305e9
\ No newline at end of file
diff --git a/generate static files.ipynb.REMOVED.git-id b/generate static files.ipynb.REMOVED.git-id
index eb342bb6..282a7f77 100644
--- a/generate static files.ipynb.REMOVED.git-id	
+++ b/generate static files.ipynb.REMOVED.git-id	
@@ -1 +1 @@
-0af47a8b54290e4c30ae0bad0fd0d344efa457a8
\ No newline at end of file
+788e818806c64f3054a07faf2926f8e377915eb6
\ No newline at end of file
diff --git a/generate_static_files.py b/generate_static_files.py
index ee120ad6..f3caf4d1 100644
--- a/generate_static_files.py
+++ b/generate_static_files.py
@@ -10,14 +10,17 @@
 import nbconvert
 
 
-# 检查路径是否存在：
+# 检查路径是否存在，删除旧的文件：
 
 # In[2]:
 
 if not os.path.exists('static files'):
     os.mkdir('static files')
 
-
+for n in glob.glob('static files/*/*/*'):
+    os.remove(n)
+    
+    
 # 文件夹：
 
 # In[3]:
@@ -32,7 +35,8 @@
            '08. object-oriented programming',
            '09. theano',
            '10. something interesting',
-           '11. useful tools'
+           '11. useful tools',
+           '12. pandas'
           ]