python命令行下print 打印错误 File "" SyntaxError: invalid syntax

终端进入python3

在命令行模式下输入一端包含循环然后输出变量的简单代码，报错

>>> str1 = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
>>> output = ''
>>> for v in str1:
...     output += v
... print(output)
  File "", line 3
    print(output)
        ^
SyntaxError: invalid syntax

百思不得其解，抓耳挠腮想了半天，得出结果：for循环下面空出两行表示一个小代码段的结束。然后再输出变量。

>>> str1 = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
>>> output = ''
>>> for v in str1:
...     output += v
... 
>>>     
... print(output)
abcdefghijklmnopqrstuvwxyz
>>> 

成功！！！