IBP banding data system: Internal maintenance specification

Converts a how-group to flat-field format.

# - - -   H o w G r o u p F i e l d . f l a t t e n   - - -

    @staticmethod
    def flatten(howGroup):
        '''Flatten a how-group.
        '''
        if  howGroup is None:
            return BLANK_HOW_GROUP
        else:
            return howGroup.value.ljust(HOW_GROUP_L)