Matrix Keypad - Optimisation

single quotes worked, thanks

I still don't get the fuction of this code:

  int k = kbValue(keyboardValue);   // maps the value of the key being pressed "keypressed" i.e. 0-9
  
  Serial.println(k);                // print the value back to the Serial view window on your PC
  delay(1000);
}

// interpret the keyboard routine
int kbValue(int kbv)