#### Example
Scaling a vector by 3.
```lua
local p1 = Vec3( 11, 22, 33)
local p2 = p1:scale( 3)
```
Since `scale()` is also used as `__mul` of Vec3's metatable, you can
shorten the above example.
```lua
local p1 = Vec3( 11, 22, 33)
local p2 = p1 * 3
```
