Pause is not a valid member of AnimationTrack ?

Hello I'm Am Not Sure Why Its Is Giving Me This The Thing That's Confusing Me Is Pause Is Supposed To Be A Valid Member?The Script is a LocalScript Inside Of StarterCharacterScripts Please Give Me Some Advice On What i Should Do.

local uis = game:GetService("UserInputService")
local Character = game.Players.LocalPlayer.Character.Humanoid
local anim = Instance.new("Animation")
anim.AnimationId = 'rbxassetid://5549362459' 
local PlayAnim = Character:LoadAnimation(anim)


uis.InputBegan:Connect(function(input)
    if input.KeyCode == Enum.KeyCode.LeftShift then
        Character.WalkSpeed = 21
        while true do
            wait(0.01)
          PlayAnim:Play()
        end
    end
end)

uis.InputEnded:Connect(function(input)
    if input.KeyCode == Enum.KeyCode.LeftShift then
        Character.WalkSpeed = 16
                while true do
            wait(0.01)
            PlayAnim:Pause()
        end
    end
end)