IBP banding data system: Internal maintenance specification

Flattens a date if there is one.

# - - -   D a t e F i e l d . f l a t t e n   - - -

    @staticmethod
    def flatten(dateField):
        '''Flatten a DateField.
        '''
        if  dateField is None:
            return BLANK_DATE
        else:
            return dateField.value