//Program: Study_ArduinoCode_31_Function4.ino
int count = 1, x = 2, y;
void setup() {
  Serial1.begin(115200);
  Serial1.println("…Start…");
}
void loop() {
  y = myFunction(x); 
  Serial1.print("k (=count*2) = ");
  Serial1.println(y);
  Serial1.println("");
  delay(1000);
}
int myFunction(int i) {
  int k = i*count;
  Serial1.print("CountCallFunction: ");
  Serial1.println(count); 
  count++;
  return k; // k is integer
}