[4 DOF Robot Arm Keyestudio][Lab 03][i-Duino UNO R3B] Gripper Test

#include <Servo.h>
Servo myservo1;
Servo myservo2;
Servo myservo3;
Servo myservo4;
int pos1 = 90, pos2 = 90, pos3 = 100, pos4 = 0;
void setup() {
  checkSW();
  myservo1.attach(A1);
  myservo2.attach(A0);
  myservo3.attach(6);
  myservo4.attach(9);

  myservo1.write(pos1);
  myservo2.write(pos2);
  myservo3.write(pos3);
  myservo4.write(pos4);
  delay(3000);
}

void loop() {

  for(pos4;pos4<100;pos4++)
  {
    myservo4.write(pos4);
    delay(5);
  }
  delay(3000);
  for(pos3;pos3>30;pos3--)
  {
    myservo3.write(pos3);
    delay(5);
  }
  delay(3000);
  for(pos4;pos4>0;pos4--)
  {
    myservo4.write(pos4);
    delay(5);
  }
  delay(3000);
  for(pos3;pos3<100;pos3++)
  {
    myservo3.write(pos3);
    delay(5);
  }
  delay(3000);
  for(pos2;pos2>30;pos2--)
  {
    myservo2.write(pos2);
    delay(5);
  }
  delay(3000);
  for(pos2;pos2<90;pos2++)
  {
    myservo2.write(pos2);
    delay(5);
  }
  delay(3000);
  for(pos3;pos3>30;pos3--)
  {
    myservo3.write(pos3);
    delay(5);
  }
  delay(3000);
  for(pos4;pos4<100;pos4++)
  {
    myservo4.write(pos4);
    delay(5);
  }
  delay(3000);
  for(pos3;pos3<100;pos3++)
  {
    myservo3.write(pos3);
    delay(5);
  }
  delay(3000);
  for(pos4;pos4>0;pos4--)
  {
    myservo4.write(pos4);
    delay(5);
  }
  delay(3000);
}
void checkSW()
{
  pinMode(7, INPUT);
  while(!digitalRead(7)){

  }

}