code: def validate_gaslimit(self, header: BlockHeader) -> None:
          
          parent_header = self.get_block_header_by_hash(header.parent_hash)
          low_bound, high_bound = compute_gas_limit_bounds(parent_header)
          if header.gas_limit < low_bound:
              raise ValidationError(
                  "The gas limit on block {0} is too low: {1}. It must be at least {2}".format(
                      encode_hex(header.hash), header.gas_limit, low_bound))
          elif header.gas_limit > high_bound:
              raise ValidationError(
                  "The gas limit on block {0} is too high: {1}. It must be at most {2}".format(
                      encode_hex(header.hash), header.gas_limit, high_bound))
docs: Validate the gas limit on the given header.