Question: Jānis Liepiņš was a conductor for which opretta composed by Johann Strauss II?
Context: Eduard "Edi" Strauss (15 March 1835 – 28 December 1916) was an Austrian composer who, together with brothers Johann Strauss II and Josef Strauss made up the Strauss musical dynasty.  He was the son of Johann Strauss I and Maria Anna Streim.  The family dominated the Viennese light music world for decades, creating many waltzes and polkas for many Austrian nobility as well as dance-music enthusiasts around Europe.  He was affectionately known in his family as 'Edi'. Jānis Liepiņš (born August 7, 1988 in Riga, Latvia) is a Latvian conductor.  Since 2014, he is the conductor at the Latvian National Opera and Ballet.  For the LNO, he has conducted for productions of Il trovatore, Le Villi.  Gianni Schicchi, Eugene Onegin, Romeo and Juliet, Scheherezade and Her Tales and La Bayadere; he was the conductor and musical director for the ballet Raymonda and operetta Die Fledermaus. Simplicius is an operetta by Johann Strauss II.  It was conceived from the work of HJC von Grimmelhausen titled "Der abenteuerliche Simplicissimus" or simply "Adventurous Simplicissimus", which was opined by many to be the 17th century's greatest German novel.  The libretto for this work was furnished by Victor Léon who was one of Vienna's promising talents of that era, with music by Johann Strauss II. Johann Strauss III (25 October 1864January 9, 1939; German: "Johann Strauß III" ; also known as Johann Eduard Strauss) was an Austrian composer whose father was Eduard Strauss, whose uncles were Johann Strauss II and Josef Strauss, and whose grandfather was Johann Strauss I.  He was unofficially entrusted with the task of upholding his family's tradition after the dissolution of the Strauss Orchestra by his father in 1901.  His talents were not fully realised during his lifetime as musical tastes had changed in the Silver Age with more popular composers such as Franz Lehár and Oscar Straus dominating the Viennese musical scene with their operettas, although his uncle, Johann Strauss II, supervised his development as a musician, a fact disputed by Eduard Strauss. Die Fledermaus (] , "The Bat", sometimes called "The Revenge of the Bat") is an operetta composed by Johann Strauss II to a German libretto by and Richard Genée. Johann Strauss II (October 25, 1825 – June 3, 1899), also known as Johann Strauss Jr., the Younger, the Son (German: "Sohn" ), Johann Baptist Strauss, was an Austrian composer of light music, particularly dance music and operettas.  He composed over 500 waltzes, polkas, quadrilles, and other types of dance music, as well as several operettas and a ballet.  In his lifetime, he was known as "The Waltz King", and was largely then responsible for the popularity of the waltz in Vienna during the 19th century. Aus den Bergen ("From the Mountains"), opus 292, is the name of a waltz composed by Johann Strauss II.  The work was first performed in Pavlovsk on October 2nd 1864, under the title "In den Bergen".  The composition was dedicated to the music critic Eduard Hanslick.  Critics commented on Strauss' waltz that "after a long time a new waltz from Johann Strauss has appeared, which is distinguished by noble and graceful character, and further distinguished by extraordinarily masterful instrumentation."  The first Viennese performance of the waltz was in the Volksgarten as part of a benefit concert commemorating Strauss' twentieth anniversary of his debut as a composer. Jānis Liepiņš (August 9, 1894 – September 2, 1964) was a Latvian painter from Riga.  He studied at J Madernieks Studio in Riga between 1909-1910, at the Kazan Art School 1911-1913, and at M Bernstein's Studio in St Petersburg 1913-1917.  He was a member of the Riga Artists' Group and Professor of painting at the Art Academy of Latvia 1940-1950.  During the 1920s Liepiņš was active in the left-wing press. The Strauss Family is a 1972 English Associated Television series of eight episodes, about the family of composers of that name, including Johann Strauss I and his sons Johann Strauss II, Eduard Strauss and Josef Strauss. Rhadamantus-Klänge ("Echoes of Rhadamantus"), Op.  94, is a waltz composed by Johann Strauss II.  It was written for the 1851 Vienna Carnival.  The title of the work was named after Rhadamanthus, one of the judges of the underworld in Greek mythology.  Eduard Strauss, the composer's youngest brother, included the waltz's opening number in his potpourri "Bluthenkranz Johann Strauss'scher Walzer" ("Garland of Strauss Waltzes"), opus 292.
Answer: he was the conductor and musical director for the ballet Raymonda and operetta Die Fledermaus.