code: function getName(func) {
    if (!util.isFunction(func)) {
      return;
    }
    if (functionsHaveNames) {
      return func.name;
    }
    var str = func.toString();
    var match = str.match(regex);
    return match && match[1];
  }
docs: based on https://github.com/ljharb/function.prototype.name/blob/adeeeec8bfcc6068b187d7d9fb3d5bb1d3a30899/implementation.js