def in_batches(batch_size = DEFAULT_BATCH_SIZE)
      Specification.new(reader, result.dup { |r| r.read_as = :batch; r.batch_size = batch_size })
    end
def in_batches(batch_size = DEFAULT_BATCH_SIZE)
      Specification.new(reader, result.dup { |r| r.read_as = :batch; r.batch_size = batch_size })
    end
Specifies that events should be obtained in batches.
 {http://railseventstore.org/docs/read/ Find out more}.

 Looping through a collection of events from the store
 can be inefficient since it will try to instantiate all
 the events at once.

 In that case, batch processing methods allow you to work
 with the records in batches, thereby greatly reducing
 memory consumption.

 @param batch_size [Integer] number of events to read in a single batch
 @return [Specification]