src/Helpers/FileHelperAsc.php
public static function open($filePath, $flags = 'r')
    {
        $file = static::ensureFileObject($filePath);
        $createMode = FileHelper::permissionsAsString(static::$fileCreateMode);
        return $file->open($flags, $createMode);
    }
public static function open($filePath, $flags = 'r')
    {
        $file = static::ensureFileObject($filePath);
        $createMode = FileHelper::permissionsAsString(static::$fileCreateMode);
        return $file->open($flags, $createMode);
    }
Open file with given flags
@param string $filePath
@param string $flags c - create, w - write, r - read, t - truncate
@return \React\Promise\PromiseInterface