def is_nan(value):
    """
    Checks if value is 'nan' or NaT

    Parameters
    ---------

    value: object
        The object to be checked that it is not nan

    Returns
    ---------

    isnan: Boolean
        True: nan
        False: not nan
    """
    isnan = str(value).lower() == 'nan'
    isnat = str(value).lower() == 'nat'
    return isnan or isnat