code: def get_tx_mapping_options(self, tx_ac):
          
          rows = self._fetchall(self._queries['tx_mapping_options'], [tx_ac])
          return rows
docs: Return all transcript alignment sets for a given transcript
          accession (tx_ac); returns empty list if transcript does not
          exist.  Use this method to discovery possible mapping options
          supported in the database
  
          :param tx_ac: transcript accession with version (e.g., 'NM_000051.3')
          :type tx_ac: str
  
          # database output
          -[ RECORD 1 ]--+------------
          hgnc           | ATM
          cds_start_i    | 385
          cds_end_i      | 9556
          tx_ac          | NM_000051.3
          alt_ac         | AC_000143.1
          alt_aln_method | splign
          -[ RECORD 2 ]--+------------
          hgnc           | ATM
          cds_start_i    | 385
          cds_end_i      | 9556
          tx_ac          | NM_000051.3
          alt_ac         | NC_000011.9
          alt_aln_method | blat