def find_cfg_file(file_name=None):
    """Look for .netmiko.yml in current dir, then ~/.netmiko.yml."""
    base_file = ".netmiko.yml"
    check_files = [base_file, os.path.expanduser("~") + "/" + base_file]
    if file_name:
        check_files.insert(0, file_name)
    for test_file in check_files:
        if os.path.isfile(test_file):
            return test_file
    raise IOError("{}: file not found in current dir or home dir.".format(base_file))