code: def argv_to_cmdline(argv):
          
          cmdline = list()
          for token in argv:
              if not token:
                  token = '""'
              else:
                  if '"' in token:
                      token = token.replace('"', '\\"')
                  if  ' ' in token  or \
                      '\t' in token or \
                      '\n' in token or \
                      '\r' in token:
                          token = '"%s"' % token
              cmdline.append(token)
          return ' '.join(cmdline)
docs: Convert a list of arguments to a single command line string.
  
          @type  argv: list( str )
          @param argv: List of argument strings.
              The first element is the program to execute.
  
          @rtype:  str
          @return: Command line string.