class_docstr: Centralized config for handling configuration loading/parsing
class_docstr_tok: ["Centralized","config","for","handling","configuration","loading\/parsing"]
code: def set_starting_timestamp(self, date_format):
      self.start_last_timestamp = self._determine_last_time(date_format)
  
imports: import calendar
  from datetime import datetime
  import json
  import re
  import time
  import backoff
  import boto3
  from botocore import client
  from botocore.exceptions import ClientError
  from streamalert.apps.exceptions import AppAuthError, AppConfigError, AppStateError
  from streamalert.shared.logger import get_logger
label_desc: Use image node_id 2 for calling the AppConfig obj's underlying member method code with example usage: obj.set_starting_timestamp(date_format) without return types