code: def find_all_headers(
          pipeline_files=[],
          label_rules=None):
      
  
      log.info("find_all_headers - START")
  
      headers = ["src_file"]
      headers_dict = {"src_file": None}
  
      if label_rules:
          headers = ["src_file", "label_value", "label_name"]
          headers_dict = {"src_file": None,
                          "label_value": None,
                          "label_name": None}
  
      for c in pipeline_files:
          df = pd.read_csv(c)
          for h in df.columns.values:
              if h not in headers_dict:
                  headers_dict[h] = "{}_{}".format(
                                      c,
                                      h)
                  headers.append(h)
          # end for all headers in the file
      # end for all files to find common_headers
  
      log.info(("headers={}")
               .format(len(headers)))
  
      log.info("find_all_headers - END")
      return headers, headers_dict
docs: find_all_headers
  
      :param pipeline_files: files to process
      :param label_rules: labeling rules