def single_permission_reader(method_name)
      for permission in joinable_type.constantize.permissions
        if method_name.to_s == "#{permission}_permission"
          return has_permission?(permission)
        end
      end
    
      raise "Unknown single_permission_reader #{method_name.inspect}"
    end
def single_permission_reader(method_name)
      for permission in joinable_type.constantize.permissions
        if method_name.to_s == "#{permission}_permission"
          return has_permission?(permission)
        end
      end
    
      raise "Unknown single_permission_reader #{method_name.inspect}"
    end
Access a single permission
 eg. manage_permission # returns true if we can manage