docs: def _large_mrca(self, ts):
          """Find the MRCA using a temporary table."""
          cursor = self.db.cursor()
  
          cursor.execute("""
              DROP TABLE IF EXISTS _mrca_temp
          """)
  
          cursor.execute("""
              CREATE TEMPORARY TABLE _mrca_temp(
                  child TEXT PRIMARY KEY REFERENCES taxa (tax_id) NOT NULL
              )
          """)
  
          cursor.executemany("""
              INSERT INTO _mrca_temp
              VALUES (?)
          """, ((tid,) for tid in ts))
          cursor.execute("""
              SELECT parent
              FROM   _mrca_temp
                     JOIN parents USING (child)
                     JOIN taxa
                       ON parent = taxa.tax_id
                     JOIN ranks USING (rank)
              GROUP  BY parent
              HAVING COUNT(*) = ?
              ORDER  BY rank_order DESC
              LIMIT  1
          """, (len(ts),))
  
          return cursor.fetchall()