add return to function.

solventmapcreator/polynomialanalysis/polynomialanalysisplotting.py

@@ -26,6 +26,7 @@ def create_bar_plot_write_to_file(input_data, filename_stem, **kwargs):
     output_filename = filename_stem + '.' + fileformat
     plt.savefig(output_filename, format=fileformat)
     plt.close(bar_plot)
+    return 0
 
 def create_bar_plot(input_data, **kwargs):
     """This creates the bar plot.