docs: 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