c# - I want an object(bird) rotate right when falling -

there code: watched tutorial on youtube (https://www.youtube.com/watch?v=dwtob3j1ytg). tried follow steps, misspelled because rotating right while falling thing not working me :( please help! if need more information ask me!

using unityengine; using system.collections;  public class birdmovement : monobehaviour {      vector3 velocity = vector3.zero;     public vector3 gravity;     public vector3 flapvelocity;     public float maxspeed = 5f;     public float forwardspeed = 1f;      bool didflap = false;      // graphic & input updates here     void update() {         if (input.getkeydown(keycode.space) || input.getmousebuttondown(0)) {             didflap = true;                 }            }      // physics engine updates here     void fixedupdate () {         velocity.x = forwardspeed;         velocity += gravity * time.deltatime;          if (didflap == true) {             didflap = false;             if(velocity.y < 0)                  velocity.y = 0;              velocity += flapvelocity;                 }          velocity = vector3.clampmagnitude (velocity, maxspeed);          transform.position += velocity * time.deltatime;          float angle = 0;         if(velocity.y < 0) {             angle = mathf.lerp (0, -90, velocity.y / maxspeed);         }          transform.rotation = quaternion.euler (0,0,angle);       } } 

i followed tutorial code looks like. missing animator

public class birdmovement : monobehaviour  {     vector3 velocity = vector3.zero;     public float flapspeed    = 100f;     public float forwardspeed = 1f;     bool didflap = false;     animator animator;     public bool dead = false;     float deathcooldown;     public bool godmode = false;      void start ()      {         animator = transform.getcomponentinchildren<animator>();          if(animator == null)              debug.logerror("failed find animator!");     }      void update()      {         if(dead)          {             deathcooldown -= time.deltatime;              // should , how comes in tutorial.             if(deathcooldown <= 0)                  if(input.getkeydown(keycode.space) || input.getmousebuttondown(0))                      application.loadlevel( application.loadedlevel );         }          else if(input.getkeydown(keycode.space) || input.getmousebuttondown(0))             didflap = true;     }       // physics engine updates here     void fixedupdate ()      {         if(dead)             return;          rigidbody2d.addforce( vector2.right * forwardspeed );          if(didflap) {             rigidbody2d.addforce( vector2.up * flapspeed );             animator.settrigger("doflap");              didflap = false;         }          if(rigidbody2d.velocity.y > 0)             transform.rotation = quaternion.euler(0, 0, 0);          else          {             float angle = mathf.lerp (0, -90, (-rigidbody2d.velocity.y / 3f) );             transform.rotation = quaternion.euler(0, 0, angle);         }     }      void oncollisionenter2d(collision2d collision) {         if(godmode)             return;          animator.settrigger("death");         dead = true;         deathcooldown = 0.5f;     } }