Let’s say I’ve got a bunch of data i want to review one segment at a time. My typical way of going through and doing something to many things in sequence would involve a for or while loop. For the moment, consider a file named ‘stuff’ that contains a filename and a particular phrase on each line. I want to see what lines in each filename match that particular phrase. There could be many more than one, so I want to be able to separate the lines and phrases. So, here’s how I’d typically go about that.