code: public function setHumidity($humidity, $serial_number = NULL) {
          $serial_number = $this->getDefaultSerial($serial_number);
          $data = json_encode(array('target_humidity' => ((double)$humidity)));
          return $this->doPOST("/v2/put/device." . $serial_number, $data);
      }
docs: Change the dual-fuel breakpoint temperature.
  
  @param float  $humidity      The target humidity value.
  @param string $serial_number The thermostat serial number. Defaults to the first device of the account.
  
  @return stdClass|bool The object returned by the API call, or FALSE on error.