def METHOD_NAME():
  print 'Usage: ', prog_name, ' [options]'
  print 'Options:'
  print '   -h | --help             : Print usage and exit'
  print '   --airport_file <file>   : Airport location file name'
  print '                            (default = ', opt_airport_file, ')'
  print '   --priority_file <file>  : Airport priority file name'
  print '                            (default = ', opt_airport_file, ')'
  print '   --out_file <file>       : Output file name'
  print '                            (default = ', opt_output_file, ')'