from datetime import datetime


def convert_unix_timestamp_to_datetime_str(unix_ts):
    """ Convert a unix timestamp in stringify datetime (UTC)

    Args:
        unix_ts (int): The timestamp in unix

    Returns:
        str: The datetime in str (UTC)

    Example:
        >>> from datetime import datetime
        >>> from utils import convert_unix_timestamp_to_datetime_str
        >>> unix_ts = 1527165350
        >>> dt_str = convert_unix_timestamp_to_datetime_str(unix_ts)
        >>> print(dt_str)
        2018-05-24T12:35:50.000000Z
    """
    timestamp = datetime.utcfromtimestamp(unix_ts)
    return timestamp.strftime('%Y-%m-%dT%H:%M:%S.%fZ')