class Foo:
    def __init__(self,prefix):
        self.prefix = prefix
         
    def foo(self,s):
        'print the length of the string with the prefix.'
        print(self.prefix + str(len(s)))

ss = '1234567890'
myfoo= Foo('>>')

for i in range(5,10):
    myfoo.foo( ss[0:i] )