Errata

Learning LangChain

Errata for Learning LangChain

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The errata list is a list of errors and their corrections that were found after the product was released. If the error was corrected in a later version or reprint the date of the correction will be displayed in the column titled "Date Corrected".

The following errata were submitted by our customers and approved as valid errors by the author or editor.

Color key: Serious technical mistake Minor technical mistake Language or formatting error Typo Question Note Update

Version Location Description Submitted By Date submitted Date corrected
Page Preface
2nd last paragraph of Tool Calling

If we parse that CSV output, and have a calculator function execute the operation 1929 - 1827, we finally get the right answer: 57 years.

should be

If we parse that CSV output, and have a calculator function execute the operation 1929 - 1872, we finally get the right answer: 57 years.

Note from the Author or Editor:
1827 should be replaced with 1872

 Minhyeok  Feb 24, 2025  Apr 25, 2025
Page 105
Inside HumanMessage()

There is a missing quote.

Current: input = {"messages": [HumanMessage('hi!)]}
Should be: input = {"messages": [HumanMessage('hi!')]}

Note from the Author or Editor:
The missing quote should be added after the exclamation mark

Rafael  Aug 02, 2025