code: def test_col():
      # The color indicates reveals the edges and the stacking
      # that is going on.
      p = ggplot(data) + geom_col(
          aes("x", "z", fill="factor(z)"), color="black"
      )
  
      assert p == "col"
  
file_path: plotnine/tests/test_geom_bar_col_histogram.py
imports: import numpy
  import pandas
  from plotnine import aes, after_stat, geom_bar, geom_col, geom_histogram, geom_text, ggplot, scale_x_sqrt
  from plotnine.stats.binning import freedman_diaconis_bins
  from .conftest import layer_data
label_desc: Use image node_id 2 for calling a global function with example usage: test_col() without return types