def load_document(id)
      raise "Can't load a document without an id (got nil)" if id.nil?

      if id.is_a?(Array)
        bulk_load id
      else
        instance = couchrest_database.get(id)
        instance.database = self if instance
        instance
      end
    end
def load_document(id)
      raise "Can't load a document without an id (got nil)" if id.nil?

      if id.is_a?(Array)
        bulk_load id
      else
        instance = couchrest_database.get(id)
        instance.database = self if instance
        instance
      end
    end
loads a document by its id(s)
 id - either a single id or an array of ids
 returns either a single document or an array of documents (if an array of ids was passed).
 returns nil if the single document could not be found. when passing an array and some documents
 could not be found these are omitted from the returned array