Access variables in outer class

outer_var.py

class Meter(object):
    def __init__(self, name, parent=None):
        self.name = name
        self.parent = parent

    def __str__(self):
        return self.name

    def __repr__(self):
       return self.__str__()

class Chart(object):
    def __init__(self, name):
        self.name = name
        self.meters = []

    def add_meter(self, meter):
        meter.parent = self
        self.meters.append(meter)

    def __str__(self):
        return str(self.meters)

ch = Chart('a')
ch.add_meter(Meter('meter1'))
ch.add_meter(Meter('meter2'))

for met in ch.meters:
    print(met, met.parent.name)