    # File lib/fog/aws/requests/rds/modify_db_instance.rb, line 47
            def modify_db_instance(db_name, apply_immediately, options={})
              response = Excon::Response.new
              if self.data[:servers][db_name]
                if self.data[:servers][db_name]["DBInstanceStatus"] != "available"
                  raise Fog::AWS::RDS::NotFound.new("DBInstance #{db_name} not available for modification")
                else
                  self.data[:modify_time] = Time.now
                  # TODO verify the params options
                  # if apply_immediately is false, all the options go to pending_modified_values and then apply and clear after either
                  # a reboot or the maintainance window
                  #if apply_immediately
                  #  modified_server = server.merge(options)
                  #else
                  #  modified_server = server["PendingModifiedValues"].merge!(options) # it appends
                  #end
                  self.data[:servers][db_name]["PendingModifiedValues"].merge!(options) # it appends
                  self.data[:servers][db_name]["DBInstanceStatus"] = "modifying"
                  response.status = 200
                  response.body = {
                    "ResponseMetadata"=>{ "RequestId"=> Fog::AWS::Mock.request_id },
                    "ModifyDBInstanceResult" => { "DBInstance" => self.data[:servers][db_name] }
                  }
                  response

                end
              else
                raise Fog::AWS::RDS::NotFound.new("DBInstance #{db_name} not found")
              end
            end