def field_name_modifier(_, __, event_dict):
    """Replace log level field name 'level' with 'serverity' to meet
    Cloud Logging's data model.
    Make sure to call this processor after structlog.stdlib.add_log_level.
    https://cloud.google.com/logging/docs/reference/v2/rpc/google.logging.v2?hl=en#google.logging.v2.LogEntry
    """
    event_dict["severity"] = event_dict["level"]
    del event_dict["level"]
    return event_dict