`.do` arguments not passed correctly

首先检查 5a-chain 中的回调链实现，以及展示 readConfig、selectFromDb、getHttpPage 和 readFile 的使用示例。跟踪参数如何通过每次 .do() 调用传递，然后验证文档中说明的回调是否接收到预期的显式参数和前一个回调的参数，而不是 undefined。

The current implementation of the callback chain in 5a-chain passes data from the previous callback but doesn't pass arguments explicitly mentioned in .do().

In usage example readConfig callback is expected to receive myConfig as an argument.

const startChain = chain()
  .do(readConfig, 'myConfig')
  .do(selectFromDb, 'select * from cities')
  .do(getHttpPage, 'http://kpi.ua')
  .do(readFile, 'README.md');

However it receives undefined instead.

So if callbacks would really depend on the previous one the chain would fail once it was called.

Also, should only the first callback in the chain receive an explicit argument, and the following ones receive their arguments from the previous one? Or should they receive both explicit and implicit arguments?