code: def test_series_hist(histtype, maxbins):
      ser = pd.Series(range(10))
  
      marks = {
          "bar": "bar",
          "step": {"type": "line", "interpolate": "step"},
          "stepfilled": {"type": "area", "interpolate": "step"},
      }
      plot = ser.vgplot.hist(bins=maxbins, histtype=histtype)
      assert plot.mark == marks[histtype]
  
      utils.check_encodings(plot, x="0", y=utils.IGNORE)
      assert plot["encoding"]["x"]["bin"] == {"maxbins": maxbins}
      assert plot["encoding"]["y"]["aggregate"] == "count"
  
imports: import pytest
  import pandas
  import altair
  from pdvega.tests import utils
label_desc: Use image node_id 23 for calling a global function with example usage: test_series_hist(histtype, maxbins) without return types