python如何调用方法

wash.py
class Washer:
 
    def __init__(self):
        self.water = 0
        self.scour = 0
 
    def add_water(self,water):
        print('Add water:',water)
        self.water = water
 
    def add_scour(self,scour):
        self.scour = scour
        print('Add scour:',self.scour)
 
    def start_wash(self):
        print('Start wash...')
if __name__ == '__main__':
    w = Washer()
    w.add_water(10)
    w.add_scour(2)
    w.start_wash()