def recall(relevance_vector, recall_base):
    """
    Calculates the recall of the given relevance vector.

    Args:
    -----
        relevance_vector : list
            A non-empty list of relevance values (0 or 1) for
            each rank of a query result.
        recall_base : int
            The number of relevant documents for the query in
            the gold standard.

    Returns:
    --------
        recall : float
            The recall of the given relevance vector.
    """
    return sum(relevance_vector) / recall_base
