def _verify_signature(message, signature, certs):
for pem in certs:<EOL><INDENT>verifier = Verifier.from_string(pem, is_x509_cert=True)<EOL>if verifier.verify(message, signature):<EOL><INDENT>return<EOL><DEDENT><DEDENT>raise AppIdentityError('<STR_LIT>')<EOL>
Verifies signed content using a list of certificates.

    Args:
        message: string or bytes, The message to verify.
        signature: string or bytes, The signature on the message.
        certs: iterable, certificates in PEM format.

    Raises:
        AppIdentityError: If none of the certificates can verify the message
                          against the signature.