code: def tracktype(self, tracktype):
          
          self._tracktype = tracktype
          if tracktype is not None:
              if 'bed' in tracktype.lower():
                  tracktype = 'bigBed'
              elif 'wig' in tracktype.lower():
                  tracktype = 'bigWig'
          self.params.update(constants.track_typespecific_fields[tracktype])
docs: When setting the track type, the valid parameters for this track type
          need to be set as well.