Problem with using spacy.matcher.matcher.Matcher.add() method - Using Spacy 2.2. version

Question

I am getting an error when trying to use spacy matcher:

ValueError: [E171] Matcher.add received invalid on_match callback argument: expected callable or None, but got: <class 'list'>

I am using spacy version 2.2.0

I was expecting extraction of President names as per the pattern defined for the matcher.