test mermaid

graph TB
    subgraph 16th
        x[Spain]
        y[Portugue]
    end
    subgraph 17th
        a[Nertherland]
        b[England]
    end
    subgraph 18th
        c[England]
        d[France]
    end
    subgraph 19th
        e[Germany]
        f[Japan]
    end
    subgraph 20th
        g[United States]
        h[Russia]
    end
    subgraph 21th
        i[China]
        j[India]
    end
    x --> y
    y --> a
    a --> b
    b --> c
    c --> d
    d --> e
    e --> f
    f --> g
    g --> h
    h --> i
    i --> j

gdoc_arrow_left_alt flink wordcount Spark Join的类型和使用 gdoc_arrow_right_alt