import time


def timestamp_datetime(value):
    """
    transfer unix time to formatted timestamp.

    Args:
        value (int): unix time.

    Returns:
        str: formatted time.
    """
    time_format = '%Y-%m-%dT%H:%M:%S%z'
    time_struct = time.localtime(value)
    return time.strftime(time_format, time_struct)