I have audio clips for an Alexa Skill in a S3 bucket and I want to create a policy file for the bucket that will allow the Lambda function (only) to access those clips. I've trying to figure out how to do this for a couple of hours with no luck. The only way the Alexa skill can access an audio clip in the bucket is if I grant read permission for each file to "everyone". Of course this makes the files available to everyone, which is what I would like to prevent. Is there an example S3 bucket policy file that I can reference?