code: def GET_blockchain_ops( self, path_info, blockchain_name, blockheight ):
          
          try:
              blockheight = int(blockheight)
              assert check_block(blockheight)
          except:
              return self._reply_json({'error': 'Invalid block'}, status_code=400)
  
          if blockchain_name != 'bitcoin':
              # not supported
              return self._reply_json({'error': 'Unsupported blockchain'}, status_code=404)
          
          blockstackd_url = get_blockstackd_url()
          nameops = blockstackd_client.get_blockstack_transactions_at(int(blockheight), hostport=blockstackd_url)
          if json_is_error(nameops):
              # error
              status_code = nameops.get('http_status', 502)
              return self._reply_json({'error': nameops['error']}, status_code=status_code)
  
          self._reply_json(nameops)
          return
docs: Get the name's historic name operations
          Reply the list of nameops at the given block height
          Reply 404 for blockchains other than those supported
          Reply 502 for any error we have in talking to the blockstack server