@staticmethod
def validate(value):
    """Validate and convert the input to a ListType.

        :param value: A comma separated string of values
        :returns: A list of unique values (lower-cased), maintaining the
                  same order
        """
    items = []
    for v in str(value).split(','):
        v_norm = v.strip().lower()
        if v_norm and v_norm not in items:
            items.append(v_norm)
    return items
