# topic - sns.Topic
# fn - _lambda.Function

filter_policy = {
    "key": sns.SubscriptionFilter.string_filter(
        match_suffixes=[".fastq", ".fastq.gz"] # param doesn't exist
    )
}
topic.add_subscription(
    subscriptions.LambdaSubscription(fn, filter_policy=filter_policy)
)

filter_policy = {"key": [{"suffix": ".fastq"}, {"suffix": ".fastq.gz"}]}
sns.CfnSubscription(
    self,
    "SubscriptionExample",
    topic_arn=topic.topic_arn,
    filter_policy=filter_policy,
    protocol="lambda",
    endpoint=fn.function_arn,
)

# I don't know how to use fn.grant_invoke on topic
lambda_.CfnPermission(
    self,
    "LambdaPermission",
    action="lambda:InvokeFunction",
    function_name=fn.function_arn,
    principal="sns.amazonaws.com",
    source_arn=topic.topic_arn,
)