OAoth魔术功能错误

I am using OAuth Class which have fucntion

class OAuth {
            public __construct ( string $consumer_key , string $consumer_secret [, string $signature_method = OAUTH_SIG_METHOD_HMACSHA1 [, int $auth_type = 0 ]] )

           public bool enableDebug ( void )
           public array getRequestToken ( string $request_token_url [, string $callback_url ] )

           }

I am calling these like this

    $oauthClient = new OAuth($consumerKey, $consumerSecret, OAUTH_SIG_METHOD_HMACSHA1, $authType);
$oauthClient->enableDebug();

if (!isset($_GET['oauth_token']) && !$_SESSION['state']) {
    $requestToken = $oauthClient->getRequestToken($temporaryCredentialsRequestUrl);
    $_SESSION['secret'] = $requestToken['oauth_token_secret'];
    $_SESSION['state'] = 1;
    header('Location: ' . $adminAuthorizationUrl . '?oauth_token=' . $requestToken['oauth_token']);
    exit;
}

giving error

 Parse error: syntax error, unexpected '__construct' (T_STRING), expecting variable (T_VARIABLE)

And Error for disableDebug

   Parse error: syntax error, unexpected 'bool' (T_STRING), expecting variable (T_VARIABLE) 

Please help what is the problem