 Complete the following phrase:  Delvalles plays explore historical and folkloric themes. He wrote a trilogy of plays dealing with events during the Paraguayan War, multiple plays exploring Paraguayan mythology and Guaraní folklore, and several librettos for musical comedies and zarzuelas. The situation of Paraguayan tet farmers is a recurring theme in his work. His novel Un viento negro A Black Wind, for which he won the 2013 Paraguayan National Prize for Literature, explores the terror of life under the repressive Stroessner dictatorship, which ruled Paraguay for 