docs: def main():
      """
      NAME
          tk03.py
  
      DESCRIPTION
          generates set of vectors drawn from TK03.gad at given lat and
          rotated about vertical axis by given Dec
  
      INPUT (COMMAND LINE ENTRY)
      OUTPUT
          dec,  inc, int
  
      SYNTAX
          tk03.py [command line options] [> OutputFileName]
  
      OPTIONS
          -n N specify N, default is 100
          -d D specify mean Dec, default is 0
          -lat LAT specify latitude, default is 0
          -rev include reversals
          -t INT  truncates  intensities to >INT uT
          -G2 FRAC  specify average g_2^0 fraction (default is 0)
          -G3 FRAC  specify average g_3^0 fraction (default is 0)
      """
      N, L, D, R = 100, 0., 0., 0
      G2, G3 = 0., 0.
      cnt = 1
      Imax = 0
      if len(sys.argv) != 0 and '-h' in sys.argv:
          print(main.__doc__)
          sys.exit()
      else:
          if '-n' in sys.argv:
              ind = sys.argv.index('-n')
              N = int(sys.argv[ind + 1])
          if '-d' in sys.argv:
              ind = sys.argv.index('-d')
              D = float(sys.argv[ind + 1])
          if '-lat' in sys.argv:
              ind = sys.argv.index('-lat')
              L = float(sys.argv[ind + 1])
          if '-t' in sys.argv:
              ind = sys.argv.index('-t')
              Imax = 1e3 * float(sys.argv[ind + 1])
          if '-rev' in sys.argv:
              R = 1
          if '-G2' in sys.argv:
              ind = sys.argv.index('-G2')
              G2 = float(sys.argv[ind + 1])
          if '-G3' in sys.argv:
              ind = sys.argv.index('-G3')
              G3 = float(sys.argv[ind + 1])
      for k in range(N):
          gh = pmag.mktk03(8, k, G2, G3)  # terms and random seed
          # get a random longitude, between 0 and 359
          lon = random.randint(0, 360)
          vec = pmag.getvec(gh, L, lon)  # send field model and lat to getvec
          if vec[2] >= Imax:
              vec[0] += D
              if k % 2 == 0 and R == 1:
                  vec[0] += 180.
                  vec[1] = -vec[1]
              if vec[0] >= 360.:
                  vec[0] -= 360.
              print('%7.1f %7.1f %8.2f ' % (vec[0], vec[1], vec[2]))