def _choose_lines_or_arcs(self, lines: bool = False, arcs: bool = False) -> None:
        """Force the data file to choose between lines and arcs."""
        assert lines or arcs
        assert not (lines and arcs)
        if lines and self._has_arcs:
            if self._debug.should("dataop"):
                self._debug.write("Error: Can't add line measurements to existing branch data")
            raise DataError("Can't add line measurements to existing branch data")
        if arcs and self._has_lines:
            if self._debug.should("dataop"):
                self._debug.write("Error: Can't add branch measurements to existing line data")
            raise DataError("Can't add branch measurements to existing line data")
        if not self._has_arcs and not self._has_lines:
            self._has_lines = lines
            self._has_arcs = arcs
            with self._connect() as con:
                con.execute_void(
                    "insert or ignore into meta (key, value) values (?, ?)",
                    ("has_arcs", str(int(arcs))),
                )
Force the data file to choose between lines and arcs.
coverage/sqldata.py