sence i cant use Item stack how do i fix

 @Override
    protected boolean processInteract(EntityPlayer player, EnumHand hand, ItemStack stack) {
    	if(stack != null && stack.getItem() == Items.SPAWN_EGG) {
    		return super.processInteract(player, hand, stack);
    	} else {
    		if(!this.isBeingRidden()) {
    			if(stack != null && stack.interactWithEntity(player, this, hand)) {
    				return true;
    			} else {
    				this.mountTo(player);
    				Minecraft.getMinecraft().gameSettings.thirdPersonView = 1;
    				return true;
    			}
    		} else {
    			return super.processInteract(player, hand, stack);
    		}
    	}


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no loger likes worldObj in


private void mountTo(EntityPlayer player) {
    	player.rotationYaw = this.rotationYaw;
    	player.rotationPitch = this.rotationPitch;

    	if(!this.worldObj.isRemote) {
    		player.startRiding(this);
    	}
    }

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no longer likes sqrt_double in

this.prevLimbSwingAmount = this.limbSwingAmount;
    		double d1 = this.posX - this.prevPosX;
    		double d0 = this.posZ - this.prevPosZ;
    		float f2 = MathHelper.sqrt_double(d1 * d1 + d0 * d0) * 4.0f;

    		if(f2 > 1.0f) {
    			f2 = 1.0f;
    		}

    		this.limbSwingAmount += (f2 - this.limbSwingAmount) * 0.4f;
    		this.limbSwing += this.limbSwingAmount;
    	} else {
    		this.jumpMovementFactor = 0.02f;
    		super.moveEntityWithHeading(strafe, forward);
    	}