original_string: public function asNull(): Primitive\NullType
      {
          if (!$this->_element instanceof Primitive\NullType) {
              throw new \UnexpectedValueException(
                  $this->_generateExceptionMessage(Element::TYPE_NULL));
          }
          return $this->_element;
      }
code: public function asNull(): Primitive\NullType
      {
          if (!$this->_element instanceof Primitive\NullType) {
              throw new \UnexpectedValueException(
                  $this->_generateExceptionMessage(Element::TYPE_NULL));
          }
          return $this->_element;
      }
code_tokens: public function asNull ( ) : Primitive \ NullType { if ( ! $ this -> _element instanceof Primitive \ NullType ) { throw new \ UnexpectedValueException ( $ this -> _generateExceptionMessage ( Element :: TYPE_NULL ) ) ; } return $ this -> _element ; }
docstring: Get the wrapped element as a null type.
  
  @throws \UnexpectedValueException If the element is not a null
  @return \ASN1\Type\Primitive\NullType
docstring_tokens: Get the wrapped element as a null type .