#!/usr/bin/env python3

# a class acting as parent class
class Person:
 "docstring of Person  class"
 def __init__(self, first, last):
   self.firstName = first
   self.lastName = last

 def printName(self):
   print(self.firstName, self.lastName)

# a child class of 'Person'
# calling '_init__' of parent class
class Student(Person):
 "docstring of Student class"

 def __init__(self, ff_name, ll_name, studentNumber = None):
   super().__init__(ff_name, ll_name) 
   if studentNumber==None:
     self.studentNumber = 0
   else:
     self.studentNumber = studentNumber

p1 = Person("John", "Doe")
p1.printName()

s1 = Student("Jane", "Ark")
s1.printName()                             # inherited 

print()
print(p1.__doc__)                          # docstrings
print(s1.__doc__)                          # docstrings
print()