import pytz
from datetime import datetime


def timestamp(time_format=None, time_zone=pytz.utc):
    """Return a formatted timestamp for embedding in files

    Args:
        time_format: A time formatter suitable for strftime
        time_zone: Time zone used to generate timestamp (Default: UTC)

    Returns:
        str: A formatted time string
    """
    time_fmt = time_format or "%Y-%m-%d %H:%M:%S (%Z)"
    return datetime.now(time_zone).strftime(time_fmt)