code: def set_exposure_scale(self, name, scale=None):
          
          name = self.roi.get_source_by_name(name).name
          if scale is None and name not in self._src_expscale:
              return
          elif scale is None:
              scale = self._src_expscale.get(name, 1.0)
          else:
              self._src_expscale[name] = scale
          self._scale_srcmap({name: scale})
docs: Set the exposure correction of a source.
  
          Parameters
          ----------
          name : str
              Source name.
  
          scale : factor
              Exposure scale factor (1.0 = nominal exposure).