code: def test_get_standard_colors_no_appending(self):
      # GH20726
  
      # Make sure not to add more colors so that matplotlib can cycle
      # correctly.
      from matplotlib import cm
  
      from pandas.plotting._matplotlib.style import get_standard_colors
  
      color_before = cm.gnuplot(range(5))
      color_after = get_standard_colors(1, color=color_before)
      assert len(color_after) == len(color_before)
  
      df = DataFrame(
          np.random.default_rng(2).standard_normal((48, 4)),
          columns=list("ABCD"),
      )
  
      color_list = cm.gnuplot(np.linspace(0, 1, 16))
      p = df.A.plot.bar(figsize=(16, 7), color=color_list)
      assert (
          p.patches[1].get_facecolor() == p.patches[17].get_facecolor()
      )
  
imports: import os
  import numpy
  import pytest
  import pandas.util._test_decorators
  from pandas import DataFrame, Index, Series, Timestamp, date_range, interval_range, period_range, plotting, read_csv
  import pandas._testing
  from pandas.tests.plotting.common import _check_colors, _check_legend_labels, _check_plot_works, _check_text_labels, _check_ticks_props
label_desc: Use image node_id 25 for calling the TestDataFramePlots obj's underlying member method code with example usage: obj.test_get_standard_colors_no_appending() without return types