APEX CODE: Automatically Convert Lead to Person Account When Event Associated

In need of an APEX code to convert a lead automatically when an event is associated with that lead * automatically convert leads when a certain type of event is created in association with a lead * convert the lead to a Person Account, and you aren't going to need to worry about also creating a new contact/opportunity * Preferably, In need of an invocable Apex class that can be launched from Process Builder when such an event is created; you tried this already with Process Builder but the "Is Converted" field is only accessible via Apex, not via declarative tools like Process Builder/Flow