Yo~!

fa5fd6351605912ec75e783cb626497b1ebe471e introduced a change where org-babel-script-escape stopped accepting numbers. This caused an issue in ob-ruby.el where when trying to evaluate something like "2 + 2", you would get the message:

  `org-babel-script-escape' expects a string

I suspect this is not the only location where this problem might arise, so I am submitting a patch so the function simply returns numbers if they are passed in rather than dying. (Because numbers don't need to be escaped, and this was the previous behaviour.)

Could you review my patch? Thanks..!