nitpick: `creep` is a better, more descriptive name that `c`. Its a bit more verbose, sure, and its pretty obvious what's going on here, but its good practice to be more descriptive than not.

Single letters should only really be used when you don't know the type of the object and you're going to have to cast it - ex `<Creep> o` where "o" just means "object".

To be fair, even at Addepar this is more of a "java" convention than a general "programming" convention - for instance, in javascript/coffeescript where there's no strict typing, anonymous functions often have single letter args. So take this with a grain of salt, I guess.