code: def protract(self, x):
          
          self.active = self.active.protract(x)
          return self.active
docs: Protract each of the `active` `Segments` by ``x`` seconds.
  
          This method subtracts ``x`` from each segment's lower bound,
          and adds ``x`` to the upper bound, while maintaining that each
          `Segment` stays within the `known` bounds.
  
          The :attr:`~DataQualityFlag.active` `SegmentList` is modified
          in place.
  
          Parameters
          ----------
          x : `float`
              number of seconds by which to protact each `Segment`.