def expand_args(**args_to_expand):
    """Expand the given lists into the length of the layers.

    This is used as a convenience so that the user does not need to specify the
    complete list of parameters for model initialization.
    IE the user can just specify one parameter and this function will expand it
    """
    layers = args_to_expand['layers']
    try:
        items = args_to_expand.iteritems()
    except AttributeError:
        items = args_to_expand.items()
    for key, val in items:
        if isinstance(val, list) and len(val) != len(layers):
            args_to_expand[key] = [val[0] for _ in layers]
    return args_to_expand
