code: def test_ser_kde():
      ser = pd.Series(range(10), name="x")
      plot = ser.vgplot.kde(bw_method="scott")
      assert plot.mark == "line"
      utils.check_encodings(
          plot,
          x=" ",
          y="x",
      )
  
imports: import pytest
  import pandas
  import altair
  from pdvega.tests import utils
label_desc: Use image node_id 29 for calling a global function with example usage: test_ser_kde() without return types