writes a comment tag to the Purr pipe

def comment(self, comment, show=False, endline=True, newpar=False):
        """writes a comment tag to the Purr pipe"""
        if not endline:
            comment += "<NOBR>"
        if newpar:
            comment += "<BR>"
        self._write("comment:%d:%s\n" % (int(show), comment))
        return self