Ex15 Study drill 6 problem

On exercise 15 for learn Python the hard way, for study drill 6 when I use “open(ex15_sample.txt)”
I get a NameError telling me ex15_sample is not defined. Why’s that?

@jonay please show us your whole code and format it like so:

your code here

Take a look at how I do it. I put quotes around the ex15_sample.txt to make it into a string.