def get_flag(var, fallback, expected=True, warn=True):
    # type: (str, Callable[..., bool], Union[bool, int], bool) -> bool
    """Use a fallback method for determining SOABI flags if the needed config
    var is unset or unavailable."""
    val = get_config_var(var)
    if val is None:
        if warn:
            logger.debug("Config variable '%s' is unset, Python ABI tag may "
                         "be incorrect", var)
        return fallback()
    return val == expected
Use a fallback method for determining SOABI flags if the needed config
    var is unset or unavailable.
stackoverflow/venv/lib/python3.6/site-packages/pip-19.0.3-py3.6.egg/pip/_internal/pep425tags.py