Log significant info using Python logging module

We would like to log significant events using Python's logging module and eventually send specific notifications to Slack. For our purposes we want to log:

1. When the doc_type isn't understood so that:
- Dev team can add keyword if it is appropriate.
- Could be a question instead or a tip-off for newsroom to follow up with.
2. When an error occurs e.g ElasticSearch is down or the nurses website is down.

未指定任何文件、测试或入口点。定位对无法识别的 doc_type 值的处理，以及 Elasticsearch 或 nurses 网站的错误路径，然后确定 Python logging 应如何记录这些事件；当每个指定事件都生成适当的日志记录时，工作即完成。

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