Convert a microsecond-precision timestamp to a native datetime.

    :type dt_str: str
    :param dt_str: The string to convert.

    :rtype: :class:`datetime.datetime`
    :returns: The datetime object created from the string.

def _rfc3339_to_datetime(dt_str):
    """Convert a microsecond-precision timestamp to a native datetime.

    :type dt_str: str
    :param dt_str: The string to convert.

    :rtype: :class:`datetime.datetime`
    :returns: The datetime object created from the string.
    """
    return datetime.datetime.strptime(dt_str, _RFC3339_MICROS).replace(tzinfo=UTC)