def _start_using(self) -> None:
        """Call this before using the database at all."""
        if self._pid != os.getpid():
            # Looks like we forked! Have to start a new data file.
            self._reset()
            self._choose_filename()
            self._pid = os.getpid()
        if not self._have_used:
            self.erase()
        self._have_used = True
Call this before using the database at all.
coverage/sqldata.py