Read this excerpt from "Rikki-Tikki-Tavi."Teddy's eyes were fixed on his father, and all his father could do was to whisper, "Sit still, Teddy. You mustn't move. Teddy, keep still.” Then Rikki-tikki came up and cried: "Turn round, Nagaina; turn and fight!”"All in good time,” said she, without moving her eyes. "I will settle my account with you presently. Look at your friends, Rikki-tikki. They are still and white; they are afraid. They dare not move, and if you come a step nearer I strike.”Who is the antagonist in this excerpt?