code: def AddPathIfNotExists(env_dict, key, path, sep=os.pathsep):
      
      try:
          is_list = 1
          paths = env_dict[key]
          if not is_List(env_dict[key]):
              paths = paths.split(sep)
              is_list = 0
          if os.path.normcase(path) not in list(map(os.path.normcase, paths)):
              paths = [ path ] + paths
          if is_list:
              env_dict[key] = paths
          else:
              env_dict[key] = sep.join(paths)
      except KeyError:
          env_dict[key] = path
docs: This function will take 'key' out of the dictionary
      'env_dict', then add the path 'path' to that key if it is not
      already there.  This treats the value of env_dict[key] as if it
      has a similar format to the PATH variable...a list of paths
      separated by tokens.  The 'path' will get added to the list if it
      is not already there.