code: function generateKey(length) {
      const possible = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
      const possibleLength = possible.length - 1;
  
      let text = '';
      _.times(getNumber(length, 16), () => {
          text += possible.charAt(_.random(possibleLength));
      });
  
      return text;
  }
docs: Generates a random alphanumeric string with length n.
  
  @static
  @memberOf _
  @category String
  @param {int} length Desired length.
  @return {string} String of random characters.
  @example
  
  _.generateKey(5);
  // => 'L7IpD'