Scripting Reference
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Animation.Rewind

function Rewind (name : String) : void

Description

Rewinds the animation named name.

JavaScript 
    // Rewind the walk animation to the start
    animation.Rewind("walk");
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        animation.Rewind("walk");
    }
}
import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        animation.Rewind('walk')

function Rewind () : void

Description

Rewinds all animations.

JavaScript 
    // Rewind all animations to the start
    animation.Rewind();
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        animation.Rewind();
    }
}
import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        animation.Rewind()