code: def rpc_get_num_blockstack_ops_at(self, block_id, **con_info):
          
          if not check_block(block_id):
              return {'error': 'Invalid block height', 'http_status': 400}
  
          db = get_db_state(self.working_dir)
          count = db.get_num_blockstack_ops_at( block_id )
          db.close()
  
          log.debug("{} name operations at {}".format(count, block_id))
          return self.success_response({'count': count})
docs: Get the number of Blockstack transactions that occured at the given block.
          Returns {'count': ..} on success
          Returns {'error': ...} on error