@property
def yaml():
    """A YAML representation of the :class:`Dataset` object. If headers have been
        set, a YAML list of objects will be returned. If no headers have
        been set, a YAML list of lists (rows) will be returned instead.

        A dataset object can also be imported by setting the :class:`Dataset.yaml` attribute: ::

            data = tablib.Dataset()
            data.yaml = '- {age: 90, first_name: John, last_name: Adams}'

        Import assumes (for now) that headers exist.
        """
    pass
