code: def list_salesforce_api_versions():
      """Helper function to return a list of supported API versions"""
      return [
          {
              "version": "20.0",
              "label": "Winter '11",
              "url": "/services/data/v20.0",
          },
          {
              "version": "21.0",
              "label": "Spring '11",
              "url": "/services/data/v21.0",
          },
          {
              "version": "26.0",
              "label": "Winter '13",
              "url": "/services/data/v26.0",
          },
      ]
  
file_path: streamalert/tests/unit/streamalert/apps/test_helpers.py
imports: import json
  import boto3
  from botocore.exceptions import ClientError, ParamValidationError
label_desc: Use image node_id 5 for calling a global function with example usage: list_salesforce_api_versions() and returns: list