generate questions: During the summers at Nohant, particularly in the years 1839–43, Chopin found quiet, productive days during which he composed many works, including his Polonaise in A-flat major, Op. 53. Among the visitors to Nohant were Delacroix and the mezzo-soprano Pauline Viardot, whom Chopin had advised on piano technique and composition. Delacroix gives an account of staying at Nohant in a letter of 7 June 1842:
What is the example given of a work produced by Frédéric during calm summers at Nohant? {sep_token} Which of the two people that visited Chopin were tutored by him on piano? {sep_token} On what date did Delacroix write a letter based on his visit at Nohant? {sep_token} What did Chopin help Pauline Viardot with? {sep_token} Who were two visitors to Chopin while in Nohant? {sep_token} What two things did Chopin advise Viardot on? {sep_token} Who wrote a letter on June 7, 1842 about a stay in Nohant? {sep_token}