How to use classes to hold data

#class test
class cA(object):
      a = 42
      def chA(self,b):
          self.a = 60
          return b

f=cA(); #  f instantiates the cA class
print f.a; #  the property 'a' of the object f will have
              the class's initial value, 42
x=f.chA(8); # the chA method of cA will change the 
              value and return the value you sent in.
print x; # that is, 8
print f.a; # however, now the 'a' property is 60