docs: def get_block_from_consensus( self, consensus_hash ):
          """
          Get the block number with the given consensus hash.
          Return None if there is no such block.
          """
          query = 'SELECT block_id FROM snapshots WHERE consensus_hash = ?;'
          args = (consensus_hash,)
  
          con = self.db_open(self.impl, self.working_dir)
          rows = self.db_query_execute(con, query, args, verbose=False)
          res = None
  
          for r in rows:
              res = r['block_id']
  
          con.close()
          return res