code: def test_chart_extend_axis(fake_writer):
      v1 = [
          2.0,
          4.9,
          7.0,
          23.2,
          25.6,
          76.7,
          135.6,
          162.2,
          32.6,
          20.0,
          6.4,
          3.3,
      ]
      v2 = [
          2.6,
          5.9,
          9.0,
          26.4,
          28.7,
          70.7,
          175.6,
          182.2,
          48.7,
          18.8,
          6.0,
          2.3,
      ]
      v3 = [
          2.0,
          2.2,
          3.3,
          4.5,
          6.3,
          10.2,
          20.3,
          23.4,
          23.0,
          16.5,
          12.0,
          6.2,
      ]
  
      bar = (
          Bar()
          .add_xaxis([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12])
          .add_yaxis("蒸发量", v1)
          .add_yaxis("降水量", v2)
          .extend_axis(
              xaxis=opts.AxisOpts(),
              yaxis=opts.AxisOpts(
                  axislabel_opts=opts.LabelOpts(formatter="{value} °C"),
                  interval=5,
              ),
          )
          .set_series_opts(label_opts=opts.LabelOpts(is_show=False))
          .set_global_opts(
              title_opts=opts.TitleOpts(title="Overlap-bar+line"),
              yaxis_opts=opts.AxisOpts(
                  axislabel_opts=opts.LabelOpts(formatter="{value} ml")
              ),
          )
      )
  
      line = (
          Line()
          .add_xaxis([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12])
          .add_yaxis("平均温度", v3, yaxis_index=0, z_level=999)
          .set_global_opts(xaxis_opts=opts.AxisOpts(type_="value"))
      )
      bar.overlap(line)
      bar.render()
      _, content = fake_writer.call_args[0]
      assert_in("xAxis", content)
  
file_path: pyecharts/test/test_chart.py
imports: from unittest.mock import patch
  from nose.tools import assert_equal, assert_in
  from pyecharts import options
  from pyecharts.charts import Line, Bar
label_desc: Use image node_id 13 for calling a global function with example usage: test_chart_extend_axis(fake_writer) without return types