# `Diffo.Provider.Extension.Verifiers.VerifyInstances`
[🔗](https://github.com/diffo-dev/diffo/blob/v0.9.0/lib/diffo/provider/extension/verifiers/verify_instances.ex#L5)

Verifies instance role declarations — no duplicates, instance_type modules must exist and extend BaseInstance

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*Consult [api-reference.md](api-reference.md) for complete listing*