python中的方法继承

Question

class Field(object):

    def __init__(self):
        self.drunks = {}

    def addDrunk(self, drunk, loc):
        if drunk in self.drunks:
            raise ValueError('Duplicate drunk')
        else:
            self.drunks[drunk] = loc

    def moveDrunk(self, drunk):
        if not drunk in self.drunks:
            raise ValueError('Drunk not in field')
        xDist, yDist = drunk.takeStep()
        currentLocation = self.drunks[drunk]
        #use move method of Location to get new location
        self.drunks[drunk] = currentLocation.move(xDist, yDist)

    def getLoc(self, drunk):
        if not drunk in self.drunks:
            raise ValueError('Drunk not in field')
        return self.drunks[drunk]


    import random


def walk(f, d, numSteps):
    start = f.getLoc(d)
    for s in range(numSteps):
        f.moveDrunk(d)
    return(start.distFrom(f.getLoc(d)))

我正在学习python，我看到了这段代码，我不明白为什么walk函数可以使用movedunk（）方法？不应该引发错误，因为moveDunk（）来自Field类？你知道吗

Answer 1

将Field类（f）的实例作为参数传递：

def walk(f, d, numSteps):
         ^