1        class Radio:
 2            def __init__(self):                              #1) constructor must be named __init__
 3                self._powerOn = False
 4                self._volume = 5
 5                self._station = 90.7
 6                self._presets = [ 90.7, 92.3, 94.7, 98.1, 105.7, 107.7 ]
 7        
 8            def togglePower(self):
 9                self._powerOn = not self._powerOn
10        
11            def setPreset(self, ind):
12                self._presets[ind] = self._station           #2) _station is an instance variable, thus self._station
13        
14            def gotoPreset(self, ind):
15                self._station = self._presets[ind]           #3) ind is a local parameter, and not an instance variable of self
16        
17            def increaseVolume(self):                        #4) Indentation of this line must be consistent with rest of the Radio class definition block
18              self._volume = self._volume + 1
19        
20            def decreaseVolume(self):
21                self._volume = self._volume - 1
22        
23            def increaseStation(self):                       #5) Must use colon when starting a new block
24                self._station = self._station + .2
25        
26            def decreaseStation(self):
27              self._station = self._station - .2             # Note: it is irrelevant whether indentation for body of this method matches indentation of other methods' bodies

    def scale(self, factor):
        for k in range(len(self._coords)):
            self._coords[k] *= factor

    def __add__(self, other):
        dim = len(self._coords)
        combined = [self._coords[k] + other._coords[k] for k in	range(dim)]
        return Point(dim, combined)