Open Graph API - Github PHP Class

I have downloaded the PHP class from github which is the wrapper for their Open Graph API. I can log in and list freinds and images etc. But what I am really struggling with is allowing for extended permissions to allow posting to a users wall.

I know somewhere I need to add scope=publ开发者_高级运维ish_stream to allow this option and can only assume it is on the getLoginUrl method but I am having next to know joy with it.

Can anyone help me.

Steve

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$loginUrl = $facebook->getLoginUrl(array('req_perms'=>'publish_stream'));