code: def get_first_key(data, search_key, default_value=None):
      """Search for the first occurrence of the given key anywhere in the nested data structure.
  
      WARNING: Only use this if you are certain the search_key can't occur more than once.
  
      Args:
          data (dict or list): Record data to search
          search_key (string): The first value associated with this key is returned
          default_value (object): Value which should be returned if no match was found
  
      Returns:
          (object) First value found or default_value if no match was found
      """
      keys = get_keys(data, search_key, max_matches=1)
      return keys[0] if keys else default_value
  
file_path: streamalert/streamalert/shared/utils.py
imports: from collections import deque
  from netaddr import IPAddress, IPNetwork
  from netaddr.core import AddrFormatError
  from streamalert.shared.logger import get_logger
  from streamalert.shared.normalize import Normalizer
label_desc: Use image node_id 3 for calling a global function with example usage: get_first_key(data, search_key, default_value) and returns: unknown