code: def get_template_parameters_s3(template_key, s3_resource):
    
    for suffix in EFConfig.PARAMETER_FILE_SUFFIXES:
      parameters_key = template_key.replace("/templates", "/parameters") + suffix
      try:
        obj = s3_resource.Object(EFConfig.S3_CONFIG_BUCKET, parameters_key)
        obj.get()
        return parameters_key
      except ClientError:
        continue
    return None
docs: Checks for existance of parameters object in S3 against supported suffixes and returns parameters file key if found
    Args:
      template_key: S3 key for template file. omit bucket.
      s3_resource: a boto3 s3 resource
    Returns:
      filename of parameters file if it exists