'Adjust the direction of the axislabel.
ACCEPTS: [ "+" | "-" ]
Note that the label_direction \'+\' and \'-\' are relative to the
direction of the increasing coordinate.'

def set_axislabel_direction(self, label_direction):

    if (label_direction not in [u'+', u'-']):
        raise ValueError(u'direction    must    be    one    of    "+",    "-"')
    if (label_direction == u'-'):
        self._axislabel_add_angle = 180
    else:
        self._axislabel_add_angle = 0
