The boy slightly cleared his throat, then began to explain:

'First I place a bait near him, to draw him in the trap, then I turn into a venomous viper and I wait for him to come. I stay on the chase, and when the mouse comes to eat the bait, I bite him. I then let him go, until the venom takes effect, then I come and swallow him, to win the fight. Thus, my enemy is destroyed forever."

The professor looked doubtful about the explanation.

'I know that ... The biggest problem ...