Convenience to string method.

def device_characteristics_str(self, indent):
        """Convenience to string method.
        """
        s = "{}\n".format(self.label)
        s += indent + "MAC Address: {}\n".format(self.mac_addr)
        s += indent + "IP Address: {}\n".format(self.ip_addr)
        s += indent + "Port: {}\n".format(self.port)
        s += indent + "Power: {}\n".format(str_map(self.power_level))
        s += indent + "Location: {}\n".format(self.location)
        s += indent + "Group: {}\n".format(self.group)
        return s