from datetime import datetime


def return_date_string(datetime_obj: datetime):
    """Get a representation of a datetime object suitable for the MangaDex API.

    .. versionadded:: 0.3
    .. versionchanged:: 0.4
        The method was changed from a private method to a seperate utility.

    :param datetime_obj: The datetime object.
    :type datetime_obj: datetime
    :return: A string representation suitable for the API.
    :rtype: str
    """
    return datetime_obj.strftime("%Y-%m-%dT%H:%M:%S")