Is your feature request related to a problem? Please describe.
Validation is often necessary, would be nice to offer a hook to keep things clean

Describe the solution you'd like
Perhaps a "validate" option that accepts a regex expression & warning message, or a function that returns true/false and warning message to allow for validation. Better yet "validate" could accept an array of these, such that specific checks could be isolated (less than 8 chars, all lowercase, etc)

Additional context
N/A