def cmd_dist(self, nm=None, ch=None):
        """dist nm=dist_name ch=chname

        Set a color distribution for the given channel.
        Possible values are linear, log, power, sqrt, squared, asinh, sinh,
        and histeq.

        If no value is given, reports the current color distribution
        algorithm.
        """
        viewer = self.get_viewer(ch)
        if viewer is None:
            self.log("No current viewer/channel.")
            return

        if nm is None:
            rgbmap = viewer.get_rgbmap()
            dist = rgbmap.get_dist()
            self.log(str(dist))
        else:
            viewer.set_color_algorithm(nm)