Prado\Collections\TMap::itemAt PHP Method

    public function itemAt($key)
    {
        return isset($this->_d[$key]) ? $this->_d[$key] : null;
    }

 /**
  * Returns the item with the specified key.
  * This overrides the parent implementation by converting the key to lower case first if CaseSensitive is false.
  * @param mixed the key
  * @return mixed the element at the offset, null if no element is found at the offset
  */
 public function itemAt($key)
 {
     return parent::itemAt($this->_caseSensitive ? $key : strtolower($key));
 }