src/Carbon/CarbonInterval.php
public function sub($unit, $value = 1)
    {
        if (is_numeric($unit)) {
            $_unit = $value;
            $value = $unit;
            $unit = $_unit;
            unset($_unit);
        }

        return $this->add($unit, -floatval($value));
    }
public function sub($unit, $value = 1)
    {
        if (is_numeric($unit)) {
            $_unit = $value;
            $value = $unit;
            $unit = $_unit;
            unset($_unit);
        }

        return $this->add($unit, -floatval($value));
    }
public function sub ( $ unit , $ value = 1 ) { if ( is_numeric ( $ unit ) ) { $ _unit = $ value ; $ value = $ unit ; $ unit = $ _unit ; unset ( $ _unit ) ; } return $ this -> add ( $ unit , - floatval ( $ value ) ) ; }
Subtract the passed interval to the current instance.

@param string|DateInterval $unit
@param int                 $value

@return static
Subtract the passed interval to the current instance .