support ethereum client interfaces

[xiangjianmeng]

go-sdk supports ethereum client interfaces as follows:

client.BalanceAt(ctx, account, blockNumber)
client.TransactionReceipt(ctx, txHash)
client.ChainID(ctx)
client.SendTransaction(ctx, tx)
client.PendingNonceAt(ctx, account)
client.NonceAt(ctx, account, blockNumber)
client.PendingCodeAt(ctx, account)
client.CodeAt(ctx, account, blockNumber)
client.EstimateGas(ctx, call)
client.SuggestGasPrice(ctx)
client.CallContract(ctx, msg, blockNumber)
client.BlockByNumber(ctx, number)
client.FilterLogs(ctx, q)
client.SubscribeFilterLogs(ctx, q, ch)
client.EthSubscribe(ctx, ch, "newHeads")
client.EthSubscribe(ctx, channel, args...)
client.CallContext(ctx, result, method, args...)
client.BatchCallContext(ctx, b)

Problem Definition

Proposal

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