In a world where humans can turn invisible at will but only when they stop breathing, what happens to Chidiebere who stands in front of a mirror, turns invisible, and then calls out to his friend Leilani to confirm whether he's invisible or not?
Provide a very brief response.
Chidiebere, when standing in front of the mirror, decides to turn invisible. To do so, he holds his breath, as that is the condition required for invisibility in this world. As Chidiebere stops breathing, he becomes invisible. 

During the invisible state, he is not reflected in the mirror because he has no visible presence. He calls out to his friend Leilani to confirm his invisibility. However, by calling out, he has to breathe out to produce the sound of his voice, which means he has to break the condition for remaining invisible.

Therefore, the moment Chidiebere calls out to Leilani, he becomes visible again because he is no longer holding his breath. Leilani can see Chidiebere as soon as he speaks, and Chidiebere also becomes visible in the mirror at the same time, therefore, confirming that he is no longer invisible.