def db_instances(options = {})
      batches = Enumerator.new do |y|
        resp = @client.describe_db_instances(options)
        resp.each_page do |page|
          batch = []
          page.data.db_instances.each do |d|
            batch << DBInstance.new(
              id: d.db_instance_identifier,
              data: d,
              client: @client
            )
          end
          y.yield(batch)
        end
      end
      DBInstance::Collection.new(batches)
    end
def db_instances(options = {})
      batches = Enumerator.new do |y|
        resp = @client.describe_db_instances(options)
        resp.each_page do |page|
          batch = []
          page.data.db_instances.each do |d|
            batch << DBInstance.new(
              id: d.db_instance_identifier,
              data: d,
              client: @client
            )
          end
          y.yield(batch)
        end
      end
      DBInstance::Collection.new(batches)
    end
@example Request syntax with placeholder values

   db_instances = rds.db_instances({
     db_instance_identifier: "String",
     filters: [
       {
         name: "String", # required
         values: ["String"], # required
       },
     ],
   })
 @param [Hash] options ({})
 @option options [String] :db_instance_identifier
   The user-supplied instance identifier. If this parameter is specified,
   information from only the specific DB instance is returned. This
   parameter isn't case-sensitive.

   Constraints:

   * If supplied, must match the identifier of an existing DBInstance.

   ^
 @option options [Array<Types::Filter>] :filters
   A filter that specifies one or more DB instances to describe.

   Supported filters:

   * `db-cluster-id` - Accepts DB cluster identifiers and DB cluster
     Amazon Resource Names (ARNs). The results list will only include
     information about the DB instances associated with the DB clusters
     identified by these ARNs.

   * `db-instance-id` - Accepts DB instance identifiers and DB instance
     Amazon Resource Names (ARNs). The results list will only include
     information about the DB instances identified by these ARNs.
 @return [DBInstance::Collection]