How to determine function name from inside a function

If I have a Bash script like:

#!/bin/bash

f() {
  # echo function name, "f" in this case
}

Is there any way to do this? This could be used in help messages such as

printf "Usage: %s: blah blah blah \n" $(basename $0) >&2; 

Only in this case what I wanted is not $0, which is the file name of the script.