Why I do not get a syntax error in this code line?

Why I do not get a syntax error in code line digitalWrite (waterPumb, LOW),
ι end this code line using comma, not using semicolon as usual.

const int analogPin = A0;    // pin that the humidety sensor is attached to
const int waterPumb = 13;   // pin that the water valve is attached to


const int threshold = 500;   // an arbitrary threshold level that's in the range of the analog input



void setup() {

  pinMode(waterPumb, OUTPUT);    // initialize the water valve pin as an output:

  Serial.begin(9600);   // initialize serial communications:
}

void loop() {
 
  int analogValue = analogRead(analogPin);  // read the value of the potentiometer:


  if (analogValue < threshold) {digitalWrite (waterPumb, HIGH); }    //if the analog value is low enough, turn on the waterPumb

delay(10000);
digitalWrite (waterPumb, LOW),          //turn on the waterPumb

  Serial.println(analogValue);                // print the analog value
  
  delay(20000);                               // delay in between reads
}

https://www.google.com/search?q=c%2B%2B+comma+operator

thank you very much!

You are welcome.