<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _cfgs_to_read(self):
 """ reads config files from various locations to build final config. """

        # use these files to extend/overwrite the conf_values.
        # Last red file always overwrites existing values!
        cfg = Config.DEFAULT_CONFIG_FILE_NAME
        filenames = [
            self.default_config_file,
            cfg,  # conf_values in current directory
            os.path.join(os.path.expanduser('~' + os.path.sep), cfg),  # config in user dir
            '.pyemma.cfg',
        ]

        # look for user defined files
        if self.cfg_dir:
            from glob import glob
            filenames.extend(glob(self.cfg_dir + os.path.sep + "*.cfg"))
        return filenames