class Foo:
  attr = "Common"
  
  def __init__(self, arg1, arg2):
    self.attr1 = arg1
    self.attr2 = arg2

  def use_me(self):
    print("Foo: use_me")
    
  def poly(self):
    print("Foo: poly")

class Bar(Foo):
  def something_new(self):
    print("Bar: something_new")
    
  def poly(self):
    print("Bar: poly")
    
class XYZ:
  def xyz(self):
    print("XYZ: xyz")
    
  def poly(self):
    print("XYZ: poly")
    
    
class Strange(Bar, XYZ):
  pass


def main():
  f = Foo(1, 3)
  b = Bar(1, 3)
  xyz = XYZ()
  s = Strange(1, 3)
  
  f.poly()   # Foo: poly
  b.poly()   # Bar: poly
  xyz.poly() # XYZ: poly
  
  # Saying the truth, this is not
  # a true polymorphism because
  # each element of the collection
  # is different type and is treated
  # as different type.
  collection = [f, b, xyz]
  
  for e in collection:
    print(type(e))
    e.poly()
    
'''
<class '__main__.Foo'>
Foo: poly
<class '__main__.Bar'>
Bar: poly
<class '__main__.XYZ'>
XYZ: poly
'''
  

if __name__ == '__main__':
  main()