def subscriptgroup_handle(tokens):
    """Process subscriptgroups."""
    internal_assert(0 < len(tokens) <= 3, "invalid slice args", tokens)
    args = []
    for arg in tokens:
        if not arg:
            arg = "None"
        args.append(arg)
    if len(args) == 1:
        return args[0]
    else:
        return "_coconut.slice(" + ", ".join(args) + ")"
Process subscriptgroups.