def METHOD_NAME(datetime_string):
    """
    Converts the input datetime string to iso datetime object
    Args:
        datetime_string (str): the datetime string
    Returns:
        (datetime.datetime) If the string is valid iso string, False otherwise
    """
    REGEX = r"^(-?(?:[1-9][0-9]*)?[0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])(\.[0-9]+)?(Z|[+-](?:2[0-3]|[01][0-9]):[0-5][0-9])?$"
    match_iso8601 = re.compile(REGEX).match
    try:
        if match_iso8601(datetime_string):
            if datetime_string.endswith("Z"):
                datetime_string = datetime_string.replace("Z", "+00:00")
            value = datetime.fromisoformat(datetime_string)
            return value
    except:
        pass
    return False