You can call the method of the parent class by its name directly:
$ cat callpm.py
class A():
def bar(self, string):
print("Hi, I'm bar, inherited from A" + string)
class B(A):
def baz(self):
self.bar(" - called by baz in B")
B().baz()
$ python --version
Python 3.6.3 :: Anaconda, Inc.
$ python callpm.py
Hi, I'm bar, inherited from A - called by baz in B