def get_movielens_dataset(variant='100K'):
    """
    Download and return one of the Movielens datasets.

    Parameters
    ----------

    variant: string, optional
         String specifying which of the Movielens datasets
         to download. One of ('100K', '1M', '10M', '20M').

    Returns
    -------

    Interactions: :class:`spotlight.interactions.Interactions`
        instance of the interactions class
    """

    if variant not in VARIANTS:
        raise ValueError('Variant must be one of {}, '
                         'got {}.'.format(VARIANTS, variant))

    url = 'movielens_{}'.format(variant)

    return Interactions(*_get_movielens(url))

    Download and return one of the Movielens datasets.

    Parameters
    ----------

    variant: string, optional
         String specifying which of the Movielens datasets
         to download. One of ('100K', '1M', '10M', '20M').

    Returns
    -------

    Interactions: :class:`spotlight.interactions.Interactions`
        instance of the interactions class
    
spotlight/datasets/movielens.py