JSONB
Passes dialect to instances of `Types` for vendor-specific type mappings.
dict
There are likely some vendor-specific enhancements (such as `JSONB` in PostgreSQL) but the current method of type guessing doesn't know anything about the underlying database.
cls
self
Not sure if this was originally intended to be a `@classmethod` but it's now written and called as a method bound to an instance of the class.