Debug gnome shell us/ru switcher

keyboard.js

    _modifiersSwitcher: function() {
        let sourceIndexes = Object.keys(this._inputSources);

        let i = 0;
        while (i < sourceIndexes.length) {
            let source = this._inputSources[sourceIndexes[i]];
            print("index: ", source.index, ", id: ", source.id);
/*
            let seen = [];
            let obj = this._inputSources;

            print(JSON.stringify(obj, function(key, val) {
               if (val != null && typeof val == "object") {
                    if (seen.indexOf(val) >= 0) {
                        return;
                    }
                    seen.push(val);
                }
                return val;
            }, '\t'));
*/
            i++;
        }

        if (sourceIndexes.length == 0) {
            releaseKeyboard();
            return true;
        }

        let is = this._currentSource;
        if (!is)
            is = this._inputSources[sourceIndexes[0]];

        print("current source index: ", is.index, ", id: ", is.id);

        let nextIndex = is.index + 1;

        print("nextIndex = ", nextIndex);

        if (nextIndex > sourceIndexes[sourceIndexes.length - 1]) {
            nextIndex = 0;
            print("nextIndex set to zero");
        }

        while (!(is = this._inputSources[nextIndex])) {
            print("skip is");
            nextIndex += 1;
        }

        print("activating ", is.id, ", index = ", is.index);
        is.activate();
        return true;
    },