#include <VarSpeedServo.h> 

VarSpeedServo myservo;    // create servo object to control a servo 

void setup() {
  myservo.attach(9);  // attaches the servo on pin 9 to the servo object 
} 

void loop() {
  myservo.write(180, 30, true);     // move to 180 degrees, use a speed of 30, wait until move is complete
  myservo.write(135, 30, true);        // move to 0 degrees, use a speed of 30, wait until move is complete
}