I find it particularly useful when I would need to look up lots of library functions I don't remember. For example, in python I recently did something (just looked it up:

    for ever my file in directory 'd' ending '.capture':
        Read file
        Split every line into A=B:C
        Make a dictionary send A to [B,C]
   Return a list of pairs [filename, dict from filename]

I don't python enough to remember reading all files in a directory, or splitting strings. I didn't even bother proof reading the English (as you can see)