async def METHOD_NAME(self):
    signed = await sign(
        document=TEST_VC_DOCUMENT,
        suite=Ed25519Signature2018(
            key_pair=self.sign_key_pair,
            verification_method=self.verification_method,
        ),
        document_loader=custom_document_loader,
        purpose=AssertionProofPurpose(),
    )
    assert signed