code: def load_topology(self,topology):
          
  
          try:
              self.universe = MDAnalysis.Universe(topology)
          except ValueError:
              print "Check your topology file - it is either missing or misspelled."
              sys.exit()
docs: Loads the topology file (e.g. GRO,PDB,INPCRD) as a MDAnalysis Universe,
          checks if it can be loaded. Needs to be run before the equivalent function
          topol.load_trajectory() and provides the snapshot that is going to be used
          for final residue placement - i.e. the residue coordinates for placement
          are taken from this file.
              Takes:
                * topology * - a topology file e.g. GRO, PDB, INPCRD, CARD, DMS
              Output:
                * self.universe * - MDAnalysis Universe