Commanded.Middleware.Uniqueness.claim_without_owner

You're seeing just the function claim_without_owner, go back to Commanded.Middleware.Uniqueness module for more information.
Link to this function

claim_without_owner(key, value, partition \\ Commanded.Middleware.Uniqueness)

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Specs

claim_without_owner(key :: term(), value :: term(), partition :: term()) ::
  :ok
  | {:error, :already_exists}
  | {:error, :unknown_error}
  | {:error, :no_adapter}

Claims a key, value, partition set or reports that this combination has already been claimed.

If partition is ommited then default partition used.