def get_parameter_for_sharding(sharding_instances):
    """Return the parameter for sharding, based on the given number of
    sharding instances.

    Args:
        sharding_instances: int. How many sharding instances to be running.

    Returns:
        list(str). A list of parameters to represent the sharding configuration.
    """
    if sharding_instances <= 0:
        raise ValueError('Sharding instance should be larger than 0')
    if sharding_instances == 1:
        return []
    else:
        return ['--capabilities.shardTestFiles=True',
                '--capabilities.maxInstances=%s' % sharding_instances]