import copy


def _confs_per_hemi(config):
    """Return a list of configs; one config per hemi found in the given config's
    'hemis' key. The new configs have an additional 'hemi' property.

    """
    confs = []

    for hemi in config['hemis']:
        c = copy.deepcopy(config)
        c['hemi'] = hemi
        confs.append(c)

    return confs