class_docstr: Provides convenience methods for accessing and modifying the alerts table.
code: def __init__(self, table_name):
      self._table = boto3.resource("dynamodb").Table(table_name)
  
file_path: streamalert/streamalert/shared/alert_table.py
imports: from datetime import datetime, timedelta
  import boto3
  from boto3.dynamodb.conditions import Attr, Key
  from streamalert.shared.alert import Alert
  from streamalert.shared.helpers.dynamodb import ignore_conditional_failure
label_desc: Use image node_id 1 to create a new AlertTable object  with example: obj = AlertTable(table_name)