text: """ Tablib - YAML Support.
  """
  
  import tablib
  import yaml
  
  
  class YAMLFormat:
      title = 'yaml'
      extensions = ('yaml', 'yml')
  
      @classmethod
      def export_set(cls, dataset):
          """Returns YAML representation of Dataset."""
  
          return yaml.safe_dump(dataset._package(ordered=False))
  
      @classmethod
      def export_book(cls, databook):
          """Returns YAML representation of Databook."""
          return yaml.safe_dump(databook._package(ordered=False))
  
      @classmethod
      def import_set(cls, dset, in_stream):
          """Returns dataset from YAML stream."""
  
          dset.wipe()
          dset.dict = yaml.safe_load(in_stream)
  
      @classmethod
      def import_book(cls, dbook, in_stream):
          """Returns databook from YAML stream."""
  
          dbook.wipe()
  
          for sheet in yaml.safe_load(in_stream):
              data = tablib.Dataset()
              data.title = sheet['title']
              data.dict = sheet['data']
              dbook.add_sheet(data)
  
      @classmethod
      def detect(cls, stream):
          """Returns True if given stream is valid YAML."""
          try:
              _yaml = yaml.safe_load(stream)
              if isinstance(_yaml, (list, tuple, dict)):
                  return True
              else:
                  return False
          except (yaml.parser.ParserError, yaml.reader.ReaderError,
                  yaml.scanner.ScannerError):
              return False
  