code: func (s *PublicBlockChainAPI) EstimateGas(ctx context.Context, args CallArgs) (hexutil.Uint64, error) {
  	return DoEstimateGas(ctx, s.b, args, rpc.PendingBlockNumber, s.b.RPCGasCap())
  }
docs: // EstimateGas returns an estimate of the amount of gas needed to execute the
  // given transaction against the current pending block.