Current revision based on jbms' feedback.

{
    define_hook("proxy_enabled_hook");
    define_hook("proxy_disabled_hook");
    define_hook("proxy_updated_hook");

    function proxy_profile() {}
    proxy_profile.prototype = {};

    define_keywords("$http", "$ssl", "$ftp", "$gopher", "$socks", "$socks_ver",
                    "$socks_dns", "$excludes");
    function proxy_profile_manual(name) {}
    proxy_profile_manual.prototype = new proxy_profile();
    proxy_profile_manual.prototype.name = null;
    proxy_profile_manual.prototype.http = null;
    proxy_profile_manual.prototype.ssl = null;
    proxy_profile_manual.prototype.ftp = null;
    proxy_profile_manual.prototype.gopher = null;
    proxy_profile_manual.prototype.socks = null;
    proxy_profile_manual.prototype.socks_ver = null;
    proxy_profile_manual.prototype.socks_dns = null;

    function proxy_profile_auto_detect() {}
    proxy_profile_auto_detect.prototype = new proxy_profile();

    keywords("$retry_min", "$retry_max", "$timeout");
    function proxy_profile_auto_config(name, url) {}
    proxy_profile_auto_config.prototype = new proxy_profile();
    proxy_profile_auto_config.prototype.name = null;
    proxy_profile_auto_config.prototype.url = null;
    proxy_profile_auto_config.prototype.retry_min = null;
    proxy_profile_auto_config.prototype.retry_max = null;
    proxy_profile_auto_config.prototype.timeout = null;

    function proxy_profile_system() {}
    proxy_profile_system.prototype = new proxy_profile();

    function proxy_profile_null() {}
    proxy_profile_null.prototype = new proxy_profile();

    function proxy_profile_unmanaged() {}
    proxy_profile_unmanaged.prototype = new proxy_profile();

    let defined_profiles = [];
    let toggle_profile = null;

    define_keywords("$http", "$ssl", "$ftp", "$gopher", "$socks", "$socks_ver",
                    "$socks_dns", "$excludes");
    function proxy_define(name) {}

    function proxy_remove(name) {}

    // 'profile' may be a defined profile or a proxy_profile instance.
    function proxy_switch(profile) {}
    interactive("proxy-switch", "Switch to a proxy profile.", function (I) {});

    function proxy_toggle() {}
    interactive("proxy-toggle", "Toggle use of proxy.", proxy_toggle);

    function proxy_mode_line_formatter_default(profile) {}

    function proxy_mode_line_enable(formatter) {}
}