A change to a class attribute does not propagate - bug or feature?

[Vesselin]

""" Please run this code. It seems that in the line:
    def __init__(self, Name = "newClass" + str(baseClass.ClassId)):
Python takes the value of baseClass.ClassId from somewhere else
I use ActivePython build 2.1.212
"""

class baseClass:
    ClassId = 1
    def __init__(self, Name):
        baseClass.ClassId += 1
        print "init in baseClass, new ClassId = ",  baseClass.ClassId
        self.ClassName = Name

class newClass(baseClass):
    def __init__(self, Name = "newClass" + str(baseClass.ClassId)):
        baseClass.__init__(self, Name)


if __name__ == '__main__':
    print "\nPrinting the initial value of the class attribute: 1/1:"
    print baseClass.ClassId
    print newClass.ClassId
    

    print "\nCreating a newClass instance"
    nClass = newClass()
    print "\nPrinting the current value of the class attribute: 2/2/2:"
    print baseClass.ClassId
    print newClass.ClassId
    print nClass.ClassId
    
    print "\nPrinting nClass.ClassName: newClass1:"
    print nClass.ClassName

    print "\nSo far so good. Now lets create another newClass instance"
    nClass2 = newClass()

    print "\nPrinting nClass2.ClassName"
    print "Expected newClass2, got newClass1:"
    print nClass2.ClassName
    
    print "\nNote that the \"real\" class attribute HAS CHANGED: 3/3/3/3:"
    print baseClass.ClassId
    print newClass.ClassId
    print nClass.ClassId
    print nClass2.ClassId
    
#Any help will be highly appreciated