def list_datasets(name=None):
reg = registry.get_registry(Dataset)<EOL>if name is not None:<EOL><INDENT>class_ = reg[name.lower()]<EOL>return _REGSITRY_NAME_KWARGS[class_]<EOL><DEDENT>else:<EOL><INDENT>return {<EOL>dataset_name: _REGSITRY_NAME_KWARGS[class_]<EOL>for dataset_name, class_ in registry.get_registry(Dataset).items()<EOL>}<EOL><DEDENT>
Get valid datasets and registered parameters.

    Parameters
    ----------
    name : str or None, default None
        Return names and registered parameters of registered datasets. If name
        is specified, only registered parameters of the respective dataset are
        returned.

    Returns
    -------
    dict:
        A dict of all the valid keyword parameters names for the specified
        dataset. If name is set to None, returns a dict mapping each valid name
        to its respective keyword parameter dict. The valid names can be
        plugged in `gluonnlp.model.word_evaluation_model.create(name)`.