Preparation for the self-construction of a carousel changer

#! /usr/bin/env python

import sys

def main(argv):

  openfile = open(argv[0], 'r')
  file_in = openfile.readlines()
  openfile.close()

  file_out = []
  for line in file_in:
    # print line
    if line.find('Z') != -1:
      words = line.rstrip('\n')
      words = words.split(' ')
      newword = ''
      for i in words:
        if i[0] == 'Z':
          newword = 'W'+ i[1:]
      if len(newword) > 0:
        words.append(newword)
        newline = ' '.join(words)
        file_out.append(newline)
    else:
      file_out.append(line)
  for item in file_out:
    print "%s" % item

if __name__ == "__main__":
   main(sys.argv[1:])

[FILTER]
PROGRAM_EXTENSION = .png,.gif,.jpg Greyscale Depth Image
PROGRAM_EXTENSION = .py Python Script
PROGRAM_EXTENSION = .nc,.tap,.ngc G-Code File
png = image-to-gcode
gif = image-to-gcode
jpg = image-to-gcode
py = python
ngc = ./nc_files/w_achse.py

[RS274NGC]
PARAMETER_FILE = linuxcnc.var
SUBROUTINE_PATH   = ../../nc_files/ngcgui_lib:../../nc_files/ngcgui_lib/utilitysubs
USER_M_PATH       = ../../nc_files/ngcgui_lib/mfiles


How to do it right?
In which directory must w-axis.py be located?
Is the file header correct?