def METHOD_NAME(form_values):
    client = oauthlib.oauth1.Client(
        form_values["oauth_consumer_key"], application_instance.shared_secret
    )
    form_values["oauth_signature"] = client.get_oauth_signature(
        oauthlib.common.Request(
            # Note the URL here does not match the `pyramid_request`
            uri="http://example.com",
            http_method="POST",
            body=form_values,
        )
    )