code: def make_trajectory(first, filename, restart=False):
      '''Factory function to easily create a trajectory object'''
      
      mode = 'w'
      if restart:
          mode = 'a'
      
      return Trajectory(first, filename, modef make_trajectory(first, filename, restart=False):
      '''Factory function to easily create a trajectory object'''
      
      mode = 'w'
      if restart:
          mode = 'a'
      
      return Trajectory(first, filename, mode)
docs: Factory function to easily create a trajectory object