Using Python programming, implement Monien and Spekenmayer backtracking algorithm for 3-CNF-SAT.. It should take a file in CNF format and return either a satisfying assignment (if any satisfying assignment exists) or 'NO' (if an input formula is unsatisfiable). The benchmarks can be found in SATLIB (go to University of British Columbia site from the bookmarked page). Take satisfiable instances from uf20-91 (20 variables, and 91 clauses), take unsatsifiable instances from uuf50-218 (50 variables, 218 clauses). [Programming Based Task]