code: def _load_significant_pathways_file(path_to_file):
      
      feature_pathway_df = pd.read_table(
          path_to_file, header=0,
          usecols=["feature", "side", "pathway"])
      feature_pathway_df = feature_pathway_df.sort_values(
          by=["feature", "side"])
      return feature_pathway_df
docs: Read in the significant pathways file as a
      pandas.DataFrame.