def measured_contexts(self) -> set[str]:
        """A set of all contexts that have been measured.

        .. versionadded:: 5.0

        """
        self._start_using()
        with self._connect() as con:
            with con.execute("select distinct(context) from context") as cur:
                contexts = {row[0] for row in cur}
        return contexts
A set of all contexts that have been measured.

        .. versionadded:: 5.0

        
coverage/sqldata.py