James Trinklein

Invalid implementation of map in Lesson 4 will break code navigation

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CodeMirror checks for and uses map on Array.prototype if it is defined. see it on [codemirror.js L7213](https://github.com/jhusain/learnrx/blob/gh-pages/assets/codemirror/codemirror.js#L7213) ``` js function map(array, f) { var out = []; for (var i...