How to use the editor/EditorManager.getFocusedEditor function in editor

.html(template)
            .insertBefore("#editor-holder");

        if (animate) {
            this._$root.addClass("popout offscreen");
            // Forcing the renderer to do a layout, which will cause it to apply the transform for the "offscreen"
            // class, so it will animate when you remove the class.
            window.getComputedStyle(this._$root.get(0)).getPropertyValue("top");
            this._$root.removeClass("popout offscreen");
        }
        
        // If something *other* than an editor (like another modal bar) has focus, set the focus 
        // to the editor here, before opening up the new modal bar. This ensures that the old
        // focused item has time to react and close before the new modal bar is opened.
        // See bugs #4287 and #3424
        if (!EditorManager.getFocusedEditor()) {
            EditorManager.focusEditor();
        }
        
        if (autoClose) {
            this._autoClose = true;
            this._$root.on("keydown", this._handleKeydown);
            window.document.body.addEventListener("focusin", this._handleFocusChange, true);
                
            // Set focus to the first input field, or the first button if there is no input field.
            // TODO: remove this logic?
            var $firstInput = $("input[type='text']", this._$root).first();
            if ($firstInput.length > 0) {
                $firstInput.focus();
            } else {
                $("button", this._$root).first().focus();
            }

function _startNewSession(editor) {
        if (!editor) {
            editor = EditorManager.getFocusedEditor();
        }
        
        if (editor) {
            lastChar = null;
            if (_inSession(editor)) {
                _endSession();
            }
            // Begin a new explicit session
            _beginSession(editor);
        }
    }

function duplicateText(editor) {
        editor = editor || EditorManager.getFocusedEditor();
        if (!editor) {
            return;
        }

        var selections = editor.getSelections(),
            delimiter = "",
            edits = [],
            rangeSels = [],
            cursorSels = [],
            doc = editor.document;

        // When there are multiple selections, we want to handle all the cursors first (duplicating
        // their lines), then all the ranges (duplicating the ranges).
        _.each(selections, function (sel) {
            if (CodeMirror.cmpPos(sel.start, sel.end) === 0) {
                cursorSels.push(sel);

function addCursorToSelection(editor, dir) {
        editor = editor || EditorManager.getFocusedEditor();
        if (editor) {
            var origSels = editor.getSelections(),
                newSels = [];
            _.each(origSels, function (sel) {
                var pos, colOffset;
                if ((dir === -1 && sel.start.line > editor.getFirstVisibleLine()) || (dir === 1 && sel.end.line < editor.getLastVisibleLine())) {
                    // Add a new cursor on the next line up/down. It's okay if it overlaps another selection, because CM
                    // will take care of throwing it away in that case. It will also take care of clipping the char position
                    // to the end of the new line if the line is shorter.
                    pos = _.clone(dir === -1 ? sel.start : sel.end);

                    // get sel column of current selection
                    colOffset = editor.getColOffset(pos);

                    pos.line += dir;

function openLine(editor, direction) {
        editor = editor || EditorManager.getFocusedEditor();
        if (!editor) {
            return;
        }

        var selections     = editor.getSelections(),
            isInlineWidget = !!EditorManager.getFocusedInlineWidget(),
            lastLine       = editor.getLastVisibleLine(),
            doc            = editor.document,
            edits          = [],
            newSelections,
            line;

        // First, insert all the newlines (skipping multiple selections on the same line),
        // then indent them all. (We can't easily do them all at once, because doMultipleEdits()
        // won't do the indentation for us, but we want its help tracking any selection changes
        // as the result of the edits.)

function handleUndoRedo(operation) {
        var editor = EditorManager.getFocusedEditor();
        var result = new $.Deferred();

        if (editor) {
            editor[operation]();
            result.resolve();
        } else {
            result.reject();
        }

        return result.promise();
    }

function moveLine(editor, direction) {
        editor = editor || EditorManager.getFocusedEditor();
        if (!editor) {
            return;
        }

        var doc             = editor.document,
            lineSelections  = editor.convertToLineSelections(editor.getSelections()),
            isInlineWidget  = !!EditorManager.getFocusedInlineWidget(),
            firstLine       = editor.getFirstVisibleLine(),
            lastLine        = editor.getLastVisibleLine(),
            totalLines      = editor.lineCount(),
            lineLength      = 0,
            edits           = [],
            newSels         = [],
            pos             = {};

        _.each(lineSelections, function (lineSel) {

function getCurrentEditorSelectedText() {
        var currentEditor = EditorManager.getFocusedEditor();
        return (currentEditor && currentEditor.getSelectedText()) || "";
    }

function splitSelIntoLines(editor) {
        editor = editor || EditorManager.getFocusedEditor();
        if (editor) {
            editor._codeMirror.execCommand("splitSelectionByLine");
        }
    }

function unindentText() {
        var editor = EditorManager.getFocusedEditor();
        if (!editor) {
            return;
        }

        editor._codeMirror.execCommand("indentLess");
    }