How to use the traverse.get function in traverse

function stringifier (insertable, node, opts) {
        var indent = opts.indent;
        
        if (insertable) {
            var prevNode = traverse.get(prev, this.path || []);
        }
        var inserted = insertable && prevNode === undefined;
        
        var indentx;
        try {
            indentx = indent ? Array(
                ((this.path || []).length + 1) * indent + 1
            ).join(' ') : '';
        } catch (e) {
            // at times we get an invalid Array size here and need to prevent crashing
            indentx = '';
        }
        if (commaFirst) indentx = indentx.slice(indent);
        
        if (Array.isArray(node)) {
            var updated = (prevNode || traverse.has(prev, this.path))

function stringifier (insertable, node, opts) {
        var indent = opts.indent;
        
        if (insertable) {
            var prevNode = traverse.get(prev, this.path || []);
        }
        var inserted = insertable && prevNode === undefined;
        
        var indentx;
        try {
            indentx = indent ? Array(
                ((this.path || []).length + 1) * indent + 1
            ).join(' ') : '';
        } catch (e) {
            // at times we get an invalid Array size here and need to prevent crashing
            indentx = '';
        }
        if (commaFirst) indentx = indentx.slice(indent);
        
        if (Array.isArray(node)) {
            var updated = (prevNode || traverse.has(prev, this.path))

function stringifier (insertable, node, opts) {
        var indent = opts.indent;
        
        if (insertable) {
            var prevNode = traverse.get(prev, this.path || []);
        }
        var inserted = insertable && prevNode === undefined;
        
        var indentx;
        try {
            indentx = indent ? Array(
                ((this.path || []).length + 1) * indent + 1
            ).join(' ') : '';
        } catch (e) {
            // at times we get an invalid Array size here and need to prevent crashing
            indentx = '';
        }
        if (commaFirst) indentx = indentx.slice(indent);
        
        if (Array.isArray(node)) {
            var updated = (prevNode || traverse.has(prev, this.path))

this.pre(function (x, key) {
                if (insertable) {
                    var obj = traverse.get(prev, this.path.concat(key));
                    if (obj === undefined) {
                        insertedKey = true;
                        set('inserted');
                    }
                }
                
                if (indent && !commaFirst) write('\n' + indentx);
                
                plainStringify(key);
                write(indent ? ' : ' : ':');
            });

this.pre(function (x, key) {
                if (insertable) {
                    var obj = traverse.get(prev, this.path.concat(key));
                    if (obj === undefined) {
                        insertedKey = true;
                        set('inserted');
                    }
                }
                
                if (indent && !commaFirst) write('\n' + indentx);
                
                plainStringify(key);
                write(indent ? ' : ' : ':');
            });

this.pre(function (x, key) {
                if (insertable) {
                    var obj = traverse.get(prev, this.path.concat(key));
                    if (obj === undefined) {
                        insertedKey = true;
                        set('inserted');
                    }
                }
                
                if (indent && !commaFirst) write('\n' + indentx);
                
                plainStringify(key);
                write(indent ? ' : ' : ':');
            });