code: def main():
      
      norm=0
      if '-f' in sys.argv:
          ind=sys.argv.index('-f')
          file=sys.argv[ind+1]
          data=np.loadtxt(file)
          dates=[2000]
      elif '-d' in sys.argv:
          ind=sys.argv.index('-d')
          dates=[float(sys.argv[ind+1])]
      elif '-r' in sys.argv:
          ind=sys.argv.index('-r')
          dates=np.loadtxt(sys.argv[ind+1])
      if '-n' in sys.argv: norm=1
      if len(sys.argv)!=0 and '-h' in sys.argv:
          print(main.__doc__)
          sys.exit()
      plt.semilogy()
      plt.xlabel('Degree (l)')
      plt.ylabel('Power ($\mu$T$^2$)')
      labels=[]
      for date in dates:
          if date!=2000: 
              gh=pmag.doigrf(0,0,0,date,coeffs=1)
              data=pmag.unpack(gh)
              Ls,Rs=pmag.lowes(data)
              labels.append(str(date))
          print(date,Rs[0])
          if norm==1: 
              Rs=old_div(np.array(Rs),Rs[0])
          #plt.plot(Ls,Rs,'ro')
          plt.plot(Ls,Rs,linewidth=2)
          plt.legend(labels,'upper right')
          plt.draw()
      input()
docs: NAME
          lowes.py
      DESCRIPTION
          Plots Lowes spectrum for input IGRF-like file
      SYNTAX
         lowes.py [options]
  
      OPTIONS:
         -h prints help message and quits
         -f FILE  specify file name with input data
         -d date specify desired date
         -r read desired dates from file
         -n normalize to dipole term
      INPUT FORMAT:
          l m g h