# File lib/openid/association.rb, line 219
    def add_allowed_type(assoc_type, session_type=nil)
      if session_type.nil?
        session_types = self.class.get_session_types(assoc_type)
      else
        self.class.check_session_type(assoc_type, session_type)
        session_types = [session_type]
      end
      for session_type in session_types do
        @allowed_types << [assoc_type, session_type]
      end
    end