Factory Method.
        Create Configobj instance and register it to self.config.
        This method also is used to create configspec instance.
        Because configspec instance also is ConfigObj instance.

def _configobj_factory(self,
                           infile,
                           raise_errors=True,
                           list_values=True,
                           file_error=True,
                           interpolation=False,
                           configspec=None,
                           stringify=True,
                           _inspec=False
                           ):
        """
        Factory Method.
        Create Configobj instance and register it to self.config.
        This method also is used to create configspec instance.
        Because configspec instance also is ConfigObj instance.
        """

        return configobj.ConfigObj(infile=infile,
                                   raise_errors=raise_errors,
                                   list_values=list_values,
                                   file_error=file_error,
                                   interpolation=interpolation,
                                   configspec=configspec,
                                   stringify=stringify,
                                   _inspec=_inspec
                                   )