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The `identifiers` argument to `aws.iam.GetPolicyDocumentStatementPrincipalArgs`  expects `Sequence[str]` type, rejecting `Sequence[Output[str]]`.

How can I use a resource output in generating an input to `aws.iam.GetPolicyDocumentStatementPrincipalArgs`'s `identifiers` argument?

`pulumi.Output.concat` and `pulumi.Output.apply` both return `Output[str]` , an incompatible type to `str` (per mypy) that causes `panic: fatal: A failure has occurred: Unrecognized structpb value kind in RPC...` .

Two failing approaches:
```identifiers=[pulumi.Output.apply(account.id, lambda id: f"arn:aws:iam::{id}:root")]
identifiers=[pulumi.Output.concat("arn:aws:iam::", account.id, ":root")]```

The approach here is to do your call to `GetPolicyDocument..()` from within an `All` or `Apply` call that coordinates and waits for the outputs you need. This will return a new output value that can be used elsewhere.

:partypus-8bit: Important to note that this approach is fine for getting resources. Get calls are synchronous and don't change the dependency graph. However, creating resources within Apply/All causes problems and should be avoided.