I know that the answer to the question "Which of the following people did not provide music for Chopin's funeral: Potocka, Franchomme, or Chopin?" is in "Some of his friends provided music at his request; among them, Potocka sang and Franchomme played the cello. Chopin requested that his body be opened after death (for fear of being buried alive) and his heart returned to Warsaw where it rests at the Church of the Holy Cross. He also bequeathed his unfinished notes on a piano tuition method, Projet de méthode, to Alkan for completion. On 17 October, after midnight, the physician leaned over him and asked whether he was suffering greatly. "No longer", he replied. He died a few minutes before two o'clock in the morning. Those present at the deathbed appear to have included his sister Ludwika, Princess Marcelina Czartoryska, Sand's daughter Solange, and his close friend Thomas Albrecht. Later that morning, Solange's husband Clésinger made Chopin's death mask and a cast of his left hand.". Can you tell me what it is?
A:
Chopin