def coalesce(self):
self.known = self.known.coalesce()<EOL>self.active = self.active.coalesce()<EOL>self.active = (self.known & self.active).coalesce()<EOL>return self<EOL>
Coalesce the segments for this flag.

        This method does two things:

        - `coalesces <SegmentList.coalesce>` the `~DataQualityFlag.known` and
          `~DataQualityFlag.active` segment lists
        - forces the `active` segments to be a proper subset of the `known`
          segments

        .. note::

            this operations is performed in-place.

        Returns
        -------
        self
            a view of this flag, not a copy.