code: def lm_tfinal(damping_times, modes):
      
  
      t_max = {}
      for lmn in modes:
          l, m, nmodes = int(lmn[0]), int(lmn[1]), int(lmn[2])
          for n in range(nmodes):
              t_max['%d%d%d' %(l,m,n)] = \
              qnm_time_decay(damping_times['%d%d%d' %(l,m,n)], 1./1000)
  
      return max(t_max.values())
docs: Return the maximum t_final of the modes given, with t_final the time
      at which the amplitude falls to 1/1000 of the peak amplitude