code: def single_traj_from_n_files(file_list, top):
      
      traj = None
      for ff in file_list:
          if traj is None:
              traj = md.load(ff, top=top)
          else:
              traj = traj.join(md.load(ff, top=top))
  
      return traj
docs: Creates a single trajectory object from a list of files