One you have added all your configuration data (Section, Element,
        ...) you need to load data from the config file.

def _load(self, exit_on_failure):
        """One you have added all your configuration data (Section, Element,
        ...) you need to load data from the config file."""
        # pylint: disable-msg=W0621
        log = logging.getLogger('argtoolbox')
        discoveredFileList = []
        if self.config_file:
            if isinstance(self.config_file, types.UnicodeType):
                discoveredFileList = self.file_parser.read(self.config_file)
            else:
                discoveredFileList = self.file_parser.readfp(
                    self.config_file,
                    "file descriptor")
        else:
            defaultFileList = []
            defaultFileList.append(self.prog_name + ".cfg")
            defaultFileList.append(
                os.path.expanduser('~/.' + self.prog_name + '.cfg'))
            defaultFileList.append('/etc/' + self.prog_name + '.cfg')
            log.debug("defaultFileList: " + str(defaultFileList))
            discoveredFileList = self.file_parser.read(defaultFileList)

        log.debug("discoveredFileList: " + str(discoveredFileList))

        if self.mandatory and len(discoveredFileList) < 1:
            msg = "The required config file was missing."
            msg += " Default config files : " + str(defaultFileList)
            log.error(msg)
            raise EnvironmentError(msg)

        log.debug("loading configuration ...")
        if exit_on_failure:
            for s in self.sections.values():
                log.debug("loading section : " + s.get_section_name())
                try:
                    s.load(self.file_parser)
                except ValueError:
                    sys.exit(1)
        else:
            for s in self.sections.values():
                log.debug("loading section : " + s.get_section_name())
                s.load(self.file_parser)

        log.debug("configuration loaded.")