'Set the option for displaying blank data in a chart.
Args:
option: A string representing the display option.
Returns:
Nothing.'

def show_blanks_as(self, option):

    if (not option):
        return
    valid_options = {'gap': 1, 'zero': 1, 'span': 1}
    if (option not in valid_options):
        warn(("Unknown    show_blanks_as()    option    '%s'" % option))
        return
    self.show_blanks = option
