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AWS Lambda received two significant improvements at the end of the year. Lambda Layers, Lambda Extensions, and Docker images for Lambda functions can be used together. Layers are helpful in multiple ways to add code to Lambda that isn’t directly part of our Lambda function. The most prevalent way layers are used is for custom runtimes. This means you can create a layer for a programming language that is not officially supported for AWS. There are even runtime layers with runtime support, so you can just pull an open-source runtime and writing code in the language of your programming language.