class_docstr: Encapsulation of a caching system that is currently backed by the filesystem
  
  The "state" of a StreamQuery execution is encapsulated by
code: def has(self, key):
      return key in self._data
  
file_path: streamalert/streamalert/scheduled_queries/state/state_manager.py
imports: from datetime import datetime
label_desc: Use image node_id 3 for calling the StateManager obj's underlying member method code with example usage: obj.has(key) and returns: unknown