Class example -i don't understand the error

[sonedap]

class SuperClass:
    def __init__(self, a1, a2):
        self.attribute1 = a1
        self.attribute2 = a2
    def getAttribute1(self):
        return self.attribute1
    def setAttribute1(self, a1):
        self.attribute1 = a1
    def getAttribute2(self):
        return self.attribute2
    def setAttribute1(self, a2):
        self.attribute2 = a2

class SubClass(SuperClass):
    def getAttribute3(self):
        return self.attribute3
    def setAttribute3(self, a3):
        elf.attribute3 = a3
    def printMessage(self):
        print("My attributes are: ", self.getAttribute1(), \
        self.getAttribute2(), self.getAttribute3())

testObject = SubClass("i", "am", "awesome!")
testObject.printMessage()

and when i run it i get this:

Error:
Traceback (most recent call last):                                                                                            
  File "/home/main.py", line 23, in <module>                                                                                  
    testObject = SubClass("Hello", "world", "!!!")                                                                            
TypeError: __init__() takes 3 positional arguments but 4 were given  

what is that about?