Is there an alphabetic equivalent of nl or seq?

I have a file where I'd like to number the lines using "the alphabet" (simple ascii a, b, c, etc.) instead of numbers. So where I could do: nl somefile I'd like to do something like: abc somefile and get output like:

a line 1 of file
b line 2 of file
c line 3 of file
...

Even an alphabetic equivalent of seq could help -- I could use paste to prefix lines. To keep things simple, my file would have 26 or less lines (so abc would not need to wrap letters like ...x, y, z, aa, ab, ac... kind of thing.)