Hello,

In the services that we run we utilise json logging for all of our error logs, I had a peruse and it seems that the current print functions either require a writer or go straight to os.Stderr.

I think it would be very helpful for us, as well as for other users of this package, if there was a function that performs the same as fprint but returns a string for use.

I've created a proof of concept here: https://github.com/jimah/errors/blob/master/errors.go#L253

For example output please see the tests.

Thank you for your time!