def METHOD_NAME(environ):
    """Return the real host for the given WSGI environment.  This takes care
    of the `X-Forwarded-Host` header.
    :param environ: the WSGI environment to get the host of.
    """
    scheme = environ.get("wsgi.url_scheme")
    if "HTTP_X_FORWARDED_HOST" in environ:
        result = environ["HTTP_X_FORWARDED_HOST"]
    elif "HTTP_HOST" in environ:
        result = environ["HTTP_HOST"]
    else:
        result = environ["SERVER_NAME"]
        if (scheme, str(environ["SERVER_PORT"])) not in (("https", "443"), ("http", "80")):
            result += ":" + environ["SERVER_PORT"]
    if result.endswith(":80") and scheme == "http":
        result = result[:-3]
    elif result.endswith(":443") and scheme == "https":
        result = result[:-4]
    return result