如何使用Python将模式过滤到另一个文件？

I have a dictionary. I want to take only the words containing a simple word pattern (i.e. "cow") and write them to another file. Each line starts with a word and then the definition. I'm still extremely new at python so I don't have a good grasp of the syntax, but the pseudocode in my head looks something like:I have a dictionary. I want to take only the wo