#include <Servo.h>
Servo leftServo;
Servo rightServo;
int angle=0;

void setup() {
  // put your setup code here, to run once:
  leftServo.attach(10);
  rightServo.attach(9);
}

void loop() {
  // put your main code here, to run repeatedly:
  for(angle=90;angle<180;angle++){
    leftServo.write(angle);
    rightServo.write(180-angle);
    delay(20);
  }
  for(angle=180;angle>=90;angle--){
    leftServo.write(angle);
    rightServo.write(180-angle);
  }
}