用pyecharts写一个3层的桑基图，第一层节点为A1和A2，大小分别为10和5，第二层为B1和B2，大小分别为9和3，第三层为C1和C2，大小分别为4和6。要求A1于B1连接，A2同时与B1和B2连接，B1和B2同时与C1连接，A2又和C2连接。

好的，这是一个关于pyecharts的问题，我可以回答它。以下是代码：

from pyecharts import options as opts
from pyecharts.charts import Sankey

nodes = [
    {"name": "A1"},
    {"name": "A2"},
    {"name": "B1"},
    {"name": "B2"},
    {"name": "C1"},
    {"name": "C2"},
]

links = [
    {"source": "A1", "target": "B1", "value": 10},
    {"source": "A2", "target": "B1", "value": 5},
    {"source": "A2", "target": "B2", "value": 5},
    {"source": "B1", "target": "C1", "value": 9},
    {"source": "B1", "target": "C2", "value": 5},
    {"source": "B2", "target": "C1", "value": 3},
    {"source": "B2", "target": "C2", "value": 5},
]

sankey = (
    Sankey()
    .add("sankey", nodes, links, linestyle_opt=opts.LineStyleOpts(opacity=0.2, curve=0.5, color="source"), label_opts=opts.LabelOpts(position="right"))
    .set_global_opts(title_opts=opts.TitleOpts(title="3层桑基图"))
)

sankey.render("sankey.html")

你可以将代码复制到Jupyter Notebook或py文件中运行，然后会生成一个名为sankey.html的文件，打开它就可以看到3层桑基图了。