problem with weapon animation -.-

hello, i want my weapon animation play when i press "w,a,s,d" and stop the animation if the buttons are not pressed and im noob on scripting so if anyone could help me :)

function Update () { if(Input.GetButtonDown("Vertical")) animation.Play("walk");

 if(Input.GetButtonDown("Horizontal"))
     animation.Play("walk");
     
 if(Input.GetButtonUp("Vertical"))
     animation.Stop("walk");
     
 if(Input.GetButtonUp("Horizontal"))
     animation.Stop("walk");                
 

}