试写一个linux命令行，可以统计所有python程序中for出现的次数，并将结果输出到某个文件中

原题：
Write a command line that counts how many times the word 'for' appears in python files (files that end with .py) within your current directory. The resulting number should be placed in a file called 'result
下面是我写的命令，但是不知道如何修改能实现输出到某个文件中的功能
grep -o for *.py | wc -l

重定向到文件就好了：

 grep -R -o for *.py | wc -l >abc.txt