Many developers finish reading the LangChain documentation yet still struggle with practical implementation. This guide skips abstract concepts and dives directly into working code examples that you can use immediately in your projects.Environment SetupBegin by installing the necessary packages:pip install langchain langchain-openaiYou'll need an OpenAI API key to get started, though the same principles apply when using domestic Chinese model providers. Simply adjust the endpoint configuration accordingly.1. LLM Invocation: The FoundationLan...