def METHOD_NAME(ntimestep):
  d.next()
  d.unscale()
  p.single(ntimestep)
  v.append('tmp.pdb','pdb')
  value = lmp.extract_compute(compute,0,0)
  xaxis.append(ntimestep)
  yaxis.append(value)
  gn.plot(xaxis,yaxis)