class_docstr: SnsPayload class
code: def service(cls):
      return "sns"
  
imports: import logging
  from streamalert.classifier.payload.payload_base import PayloadRecord, RegisterInput, StreamPayload
  from streamalert.shared.logger import get_logger
label_desc: Use image node_id 1 for calling the SnsPayload obj's underlying member method code with example usage: obj.service(cls) and returns: str