class_docstr: OutputDispatcher is the base class to handle routing alerts to outputs
  
  Public methods:
      format_output_config: returns a formatted version of the outputs configuration
          that is to be written to disk
      get_user_defined_properties: returns any properties for this output that must be
          provided by the user. must be implemented by subclasses
      dispatch: handles the actual sending of alerts to the configured service. must
          be implemented by subclass
docstr: Loads a dict of credentials relevant to this output descriptor
  
  Args:
      descriptor (str): unique identifier used to look up these credentials
  
  Returns:
      dict: the loaded credential info needed for sending alerts to this service
          or None if nothing gets loaded
docstr_tok: ["Loads","a","dict","of","credentials","relevant","to","this","output","descriptor","Args",":","descriptor","(","str",")",":","unique","identifier","used","to","look","up","these","credentials","Returns",":","dict",":","the","loaded","credential","info","needed","for","sending","alerts","to","this","service","or","None","if","nothing","gets","loaded"]
code: def _load_creds(self, descriptor):
      """Loads a dict of credentials relevant to this output descriptor
  
      Args:
          descriptor (str): unique identifier used to look up these credentials
  
      Returns:
          dict: the loaded credential info needed for sending alerts to this service
              or None if nothing gets loaded
      """
      return self._credentials_provider.load_credentials(descriptor)
  
imports: from abc import ABCMeta, abstractmethod
  from collections import namedtuple
  import requests
  from requests.exceptions import Timeout
  import urllib3
  import backoff
  from streamalert.alert_processor.outputs.credentials.provider import OutputCredentialsProvider
  from streamalert.shared.backoff_handlers import backoff_handler, success_handler, giveup_handler
  from streamalert.shared.helpers.boto import REGION
  from streamalert.shared.logger import get_logger
label_desc: Use image node_id 2 for calling the OutputDispatcher obj's underlying member method code with example usage: obj._load_creds(descriptor) and returns: self