Question: What was the profession of both Sergei Prokofiev and Philip Glass?
Context: Semyon Kotko (Russian: Семён Котко ), Op. 81, is an opera in five acts by Sergei Prokofiev to a libretto by Sergei Prokofiev and Valentin Katayev based on Katayev's 1937 novel "I, Son of Working People" (Russian: Я, сын трудового народа… ).  It was premiered on 23 June 1940 at the Stanislavsky Opera Theatre in Moscow. Sergei Olegovich Prokofieff (16 January 1954 – 26 July 2014) was a Russian anthroposophist.  He was the grandson of the composer Sergei Prokofiev and his first wife Lina Prokofiev, and the son of Oleg Prokofiev and his first wife Sofia Korovina.  Born in Moscow, he studied fine arts and painting at the Moscow School of Art.  He encountered anthroposophy in his youth, and soon made the decision to devote his life to it. Sergei Prokofiev's Lieutenant Kijé (Russian: Поручик Киже , "Poruchik Kizhe") music was originally written to accompany the film of the same name, produced by the Belgoskino film studios in Leningrad in 1933–34 and released in March 1934.  It was Prokofiev's first attempt at film music, and his first commission from within the Soviet Union; he had lived abroad since the 1917 October Revolution.  After the film's release, Prokofiev adapted the music into what became a popular orchestral suite, his Op.  60. Visions fugitives, Op. 22, are a series of short piano pieces composed by Russian composer Sergei Prokofiev (1891–1953) between 1915 and 1917.  They were premiered by Prokofiev on April 15, 1918 in Petrograd, Soviet Union.  They were written individually, many for specific friends of Prokofiev's, and he originally referred to them as his "doggies" because of their "bite".  In August 1917, Prokofiev played them for Russian poet Konstantin Balmont, and others, at the home of a mutual friend.  Balmont was inspired to compose a sonnet on the spot, called "a magnificent improvisation" by Prokofiev who named the pieces ""Mimolyotnosti"" from these lines in Balmont's poem: ""In every fleeting vision I see worlds, Filled with the fickle play of rainbows"".  A French-speaking friend at the house, Kira Nikolayevna, immediately provided a French translation for the pieces: "Visions Fugitives".  Prokofiev often performed only a couple of them at a time as encores at the end of his performances. Sergei Prokofiev set to work on his Piano Concerto No. 2 in G minor, Op. 16, in 1912 and completed it in 1913.  But this concerto is lost; the score was destroyed in a fire following the Russian Revolution.  Prokofiev reconstructed the work in 1923, two years after finishing his Third Concerto, and declared it to be “so completely rewritten that it might almost be considered [Concerto] No. 4”; indeed its orchestration has features that clearly postdate the 1921 concerto.  Performing as solo pianist, Prokofiev premiered this surviving “No. 2” in Paris on 8 May 1924 with Serge Koussevitzky conducting.  It is dedicated to the memory of Maximilian Schmidthof, a friend of Prokofiev's at the St. Petersburg Conservatory who had killed himself in 1913. Sergei Sergeyevich Prokofiev ( ; Russian: Сергей Сергеевич Прокофьев , "Sergej Sergejevič Prokofjev" ; 27 April 1891 – 5 March 1953) was a Soviet composer, pianist and conductor.  As the creator of acknowledged masterpieces across numerous musical genres, he is regarded as one of the major composers of the 20th century.  His works include such widely heard works as the March from "The Love for Three Oranges," the suite "Lieutenant Kijé", the ballet "Romeo and Juliet" – from which "Dance of the Knights" is taken – and "Peter and the Wolf."  Of the established forms and genres in which he worked, he created – excluding juvenilia – seven completed operas, seven symphonies, eight ballets, five piano concertos, two violin concertos, a cello concerto, a Symphony-Concerto for cello and orchestra, and nine completed piano sonatas. Tara Hugo sings Philip Glass is a 2012 album by mezzo-soprano and actress Tara Hugo of songs of composer Philip Glass.  The recording project was initiated by Glass himself who asked collaborator and producer Kurt Munkacsi to present pieces that Glass had composed for larger music ensembles as a song recital for small ensemble.  The recital album includes songs Glass had composed with or for singers Leonard Cohen (Book of Longing), Natalie Merchant, Mick Jagger and poet Allen Ginsberg.  The album also includes new arrangements by Trevor Gureckis of Glass instrumental music set to new lyrics written by Tara Hugo. The Philip Glass Ensemble is a musical group founded by composer Philip Glass in 1968 to serve as a performance outlet for his experimental minimalist music.  The Ensemble's instrumentation became a hallmark of Glass's early minimalist style.  After Glass wrote his first opera, "Einstein on the Beach", for the Ensemble in 1976, he began to compose for other instrumentation more frequently, but he still retains the core ensemble instrumentation. Sergei Prokofiev's Violin Sonata No. 2 in D Major, Op. 94a (sometimes written as Op. 94bis), was based on the composer's own Flute Sonata in D, Op. 94, written in 1942 but arranged for violin in 1943 when Prokofiev was living in Perm in the Ural Mountains, a remote shelter for Soviet artists during the Second World War.  Prokofiev transformed the work into a violin sonata at the prompting of his close friend violinist David Oistrakh.  It was premiered on 17 June 1944 by David Oistrakh and Lev Oborin. Philip Morris Glass (born January 31, 1937) is an American composer.  He is widely regarded as one of the most influential musicians of the late 20th century.
Answer: composer