/** * Compares two values and returns: * true when the first value is less than the second value. * false when the first value is greater than or equivalent to the second value. * * @see http://docs.mongodb.org/manual/reference/operator/aggregation/lt/ * @see Expr::lt * @param mixed|Expr $expression1 * @param mixed|Expr $expression2 * @return self */ public function lt($expression1, $expression2) { $this->expr->lt($expression1, $expression2); return $this; }