'Set the direction in which theta increases.
clockwise, -1:
Theta increases in the clockwise direction
counterclockwise, anticlockwise, 1:
Theta increases in the counterclockwise direction'

def set_theta_direction(self, direction):

    if (direction in (u'clockwise',)):
        self._direction = (-1)
    elif (direction in (u'counterclockwise', u'anticlockwise')):
        self._direction = 1
    elif (direction in (1, (-1))):
        self._direction = direction
    else:
        raise ValueError(u'direction    must    be    1,    -1,    clockwise    or    counterclockwise')
