Air is not able to replace blocks.

Running the following code showes You that air block is not able to replace glowstone or other blocks. Is it correct or failer? 

 
player.onChat("napis", function () {
blocks.print(
"Ahoj",
Block.Glowstone,
positions.create(0,0,20),
CompassDirection.West
)
loops.pause(2000)
blocks.print(
"Ahoj",
Block.Air,
positions.create(0,0,20),
CompassDirection.West
)
})
 
Thank you.