def rollback
      begin
        check
        
        @data.each_key do |collection|
          @connection[collection].drop
        end
      rescue CollectionsNotEmptyError => e
        raise RollbackIllegalError, "The collections weren't empty to begin with, rollback aborted."
      end
    end
def rollback
      begin
        check
        
        @data.each_key do |collection|
          @connection[collection].drop
        end
      rescue CollectionsNotEmptyError => e
        raise RollbackIllegalError, "The collections weren't empty to begin with, rollback aborted."
      end
    end
Empties the collections, only if they were empty to begin with