docs: function prepareStackTrace(error, stack) {
    // Store source maps in a cache so we don't load them more than once when
    // formatting a single stack trace (don't cache them forever though in case
    // the files change on disk and the user wants to see the updated mapping)
    var cache = {};
    return error + stack.map(function(frame) {
      return '\n    at ' + wrapCallSite(cache, frame);
    }).join('');
  }