code: def _load_kgXref(filename):
          
          try:
              df = pd.read_table(
                  filename,
                  names=[
                      "kgID",
                      "mRNA",
                      "spID",
                      "spDisplayID",
                      "geneSymbol",
                      "refseq",
                      "protAcc",
                      "description",
                      "rfamAcc",
                      "tRnaName",
                  ],
                  index_col=0,
                  dtype=object,
              )
              return df
          except Exception as err:
              print(err)
              return None
docs: Load UCSC kgXref table.
  
          Parameters
          ----------
          filename : str
              path to kgXref file
  
          Returns
          -------
          df : pandas.DataFrame
              kgXref table if loading was successful, else None