Is it possible to extend joi to allow for a '$' in the number() validation?

My input is a string like "$12.34". When I attempt to validate this using Joi.number() I receive an error "{Field} must be a number". All I need is to remove the $ and it works fine. Is there any way to do this in the schema definition so that I don't have to scrub my incoming data before calling validate?

```
const results = Joi.number().validate("$12.34") // fails
const results = Joi.number().validate("12.34") // succeeds

```