title: Graph API Check IN
body: <p>Hi I am developing an application that will communicate with Facebook Graph API to check in user at a particular location (only one). </p>
  
  <p>1) I let the user sign in, and ask for authorization to publish/sign into locations
  2) I get the token from facebook and thus acquire the credentials</p>
  
  <p>How do I check in a user? at a location ?</p>