a connection handle returned by dbConnect or a
zero-argument function that returns a connection handle.
schemas
a character vector of distinct schema names. These schemas will be loaded
into the dbi.catalog. By default (when schemas is missing),
dbi.catalog loads all available schemas.
# chinook.duckdb is a zero-argument function that returns a DBI handle(db <- dbi.catalog(chinook.duckdb))
# list schemasls(db)
# list the tables in the schema 'main'ls(db$main)