One-step look-up; returns a counterpart for the given string, as
    determined from the config file(s) via ConfigFromFile.
    config_file is read after ~/.counterc, if present, making its
    values take precedence over those in ~/.counterc.

    :param string: The string to find the counterpart of.
    :param config_file: Path to a config file to guide the mapping.
           Default is to use ./counterc and/or ~/.countrc.
    :return: String value, the counterpart of the input string.

def map_counterpart(string, config_file=None):
    """One-step look-up; returns a counterpart for the given string, as
    determined from the config file(s) via ConfigFromFile.
    config_file is read after ~/.counterc, if present, making its
    values take precedence over those in ~/.counterc.

    :param string: The string to find the counterpart of.
    :param config_file: Path to a config file to guide the mapping.
           Default is to use ./counterc and/or ~/.countrc.
    :return: String value, the counterpart of the input string.

    """
    skip_home_flag = config_file is not None
    mapping = get_counterpart_mapping(config_file, skip_home_flag)
    return mapping[string]