Pinq\Expressions\Expression::getType PHP Method

    public static final function getType()
    {
        return get_called_class();
    }

 protected function getMetadata(O\Expression $expression)
 {
     if (!isset($this->metadata[$expression])) {
         throw new TypeException('Cannot get metadata for expression of type \'%s\': the expression has no associated metadata', $expression->getType());
     }
     return $this->metadata[$expression];
 }