parameters: (request, settings,next=None)
return_statement: return fb
docstring: Used for redirecting the user to the Facebook
      login page if not already logged in.
  
      Usage:
        require_login(request,settings)
docstring_summary: Used for redirecting the user to the Facebook
      login page if not already logged in.
docstring_tokens: Used for redirecting the user to the Facebook login page if not already logged in .
function: def require_login(request, settings,next=None):
      """
      Used for redirecting the user to the Facebook
      login page if not already logged in.
  
      Usage:
        require_login(request,settings)
      """
      if not request.facebook: add_instance(request,settings)
      fb = request.facebook
      if not fb.check_session(request):
          redirect(fb.get_login_url(next=next))
      return fb
function_tokens: def require_login ( request , settings , next = None ) : if not request . facebook : add_instance ( request , settings ) fb = request . facebook if not fb . check_session ( request ) : redirect ( fb . get_login_url ( next = next ) ) return fb