Nick Vivarelli International CorrespondentNew York-based distribution company Grasshopper Film and Gratitude Films have jointly acquired U.S. distribution rights to Italian director Michelangelo Frammartino’s Venice Special Jury Prize winner “Il Buco,” about a group of speleologists who in 1961 discover Europe’s deepest cave.The deal was negotiated by Ryan Krivoshey of Grasshopper Film with Nadine Rothschild of Paris and Berlin-based Coproduction Office on the eve of the U.S.