Can you describe the story of Cholkar and his vow to Sai Baba?

The story of Cholkar is a powerful illustration of faith and Sai Baba's omniscience. As recounted in Chapter 15, Cholkar was a poor man whose livelihood depended on passing an examination. He made a vow to Baba that if he passed, he would visit Shirdi and distribute sugar candy. After passing, he was unable to afford the journey immediately and, as a personal penance, gave up eating sugar entirely, even in his tea. When he finally reached Shirdi and fulfilled his vow, Baba demonstrated his awareness of this secret sacrifice by instructing Mr. Jog to give Cholkar tea that was "well-filled with sugar," confirming for Cholkar that his devotion and hardship were known.