parameters: (option, opt_str, value, parser)
docstring: An optparser callback that saves an option as the absolute pathname
      of an existing executable.
docstring_summary: An optparser callback that saves an option as the absolute pathname
      of an existing executable.
docstring_tokens: An optparser callback that saves an option as the absolute pathname of an existing executable .
function: def optparser_store_abspath_exe(option, opt_str, value, parser):
      """ An optparser callback that saves an option as the absolute pathname
      of an existing executable.
      """
  
      if not os.access(value, os.X_OK):
          raise optparse.OptionValueError("'%s' is not an executable" % value)
  
      setattr(parser.values, option.dest, os.path.abspath(value))
function_tokens: def optparser_store_abspath_exe ( option , opt_str , value , parser ) : if not os . access ( value , os . X_OK ) : raise optparse . OptionValueError ( "'%s' is not an executable" % value ) setattr ( parser . values , option . dest , os . path . abspath ( value ) )