League\Monga\Query\Update::increment PHP Method

Increments a field value.

public increment ( string $field, integer $by = 1 ) : object
$field	string	field to increment
$by	integer	value to increment by
return	object	$this

    public function increment($field, $by = 1)
    {
        return $this->update('$inc', $field, (int) $by);
    }

Update