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Use case description

Hello everyone.

After incorporating serverless-python-requirements into the framework, I encountered a problem: there's no way to create separate layers, each with its own dependencies.

Let's say I have three functions:

cognito_post_confirmation - it only needs pydantic
cognito_post_authentication - it only needs ulid
shop - it needs FastAPI, meaning it will automatically install pydantic

To keep size of functions small and uptimize coldstart, my idea was to create three layers:

clear - for functions with minimal packages - only ulid
pydantic - for functions that only require pydantic
fastapi - for functions that require FastaAPI

and I'll include these layers in the corresponding functions.

As far as I know, the serverless-python-requirements plugin allows you to set dependencies for layers. However, in new versions of the serverless framework, it has been integrated into the framework, and now the "layer: true" parameter builds a single dependency layer, uniform for all. Question:

1. Am I misunderstanding something?
2. Is there another way to set a separate dependency for each layer using a separate requirements.txt file?

Proposed solution (optional)

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