AllBuckets/temp/test1/t1.txt
 AllBuckets/temp/test1/t2.gz

def lambda_handler(event, context):
  bucket = event['Records'][0]['s3']['bucket']['name']
  key = urllib.unquote_plus(event['Records'][0]['s3']['object']['key'].encode('utf8'))
  try:
    response = s3.get_object(Bucket=bucket, Key=key)
    if [ response == "t1.txt"]
      print("CONTENT TYPE: " + response['ContentType'])
      return response['ContentType']