Attempt to load config from file.

        If the command specified a --config parameter, then load that config file.
        Otherwise, the user's home directory takes precedence over a system wide config.
        Config file in the user's dir should be named ".cronyrc".
        System wide config should be located at "/etc/crony.conf"

def load_config(self, custom_config):
        """Attempt to load config from file.

        If the command specified a --config parameter, then load that config file.
        Otherwise, the user's home directory takes precedence over a system wide config.
        Config file in the user's dir should be named ".cronyrc".
        System wide config should be located at "/etc/crony.conf"
        """
        self.config = configparser.ConfigParser()

        if custom_config:
            self.config.read(custom_config)
            return f'Loading config from file {custom_config}.'

        home = os.path.expanduser('~{}'.format(getpass.getuser()))
        home_conf_file = os.path.join(home, '.cronyrc')
        system_conf_file = '/etc/crony.conf'

        conf_precedence = (home_conf_file, system_conf_file)
        for conf_file in conf_precedence:
            if os.path.exists(conf_file):
                self.config.read(conf_file)
                return f'Loading config from file {conf_file}.'

        self.config['crony'] = {}
        return 'No config file found.'