fix bugs

Author: xianhu

Diff for: python_base.py

@@ -292,7 +292,7 @@ def __missing__(self, key):
 #-- 元组和列表的唯一区别在于元组是不可变对象，列表是可变对象
     a = [1, 2, 3]           # a[1] = 0, OK
     a = (1, 2, 3)           # a[1] = 0, Error
-    a = ([1, 2])            # a[0][1] = 0, OK
+    a = ([1, 2],)           # a[0][1] = 0, OK
     a = [(1, 2)]            # a[0][1] = 0, Error
 
 #-- 元组的特殊语法: 逗号和圆括号