code: async def fetch_state(self, request):
          
          error_traps = [
              error_handlers.InvalidAddressTrap,
              error_handlers.StateNotFoundTrap]
  
          address = request.match_info.get('address', '')
          head = request.url.query.get('head', None)
  
          head, root = await self._head_to_root(head)
          response = await self._query_validator(
              Message.CLIENT_STATE_GET_REQUEST,
              client_state_pb2.ClientStateGetResponse,
              client_state_pb2.ClientStateGetRequest(
                  state_root=root, address=address),
              error_traps)
  
          return self._wrap_response(
              request,
              data=response['value'],
              metadata=self._get_metadata(request, response, head=head))
docs: Fetches data from a specific address in the validator's state tree.
  
          Request:
              query:
                  - head: The id of the block to use as the head of the chain
                  - address: The 70 character address of the data to be fetched
  
          Response:
              data: The base64 encoded binary data stored at that address
              head: The head used for this query (most recent if unspecified)
              link: The link to this exact query, including head block