human
Complete the below
def implemented_by_keychain(func):

    ''''Call a prefixed function based on \'namespace\'.'
    '''

=====
Write me a the Python program you requested?
assistant
#Here is the Python program you requested.
    @wraps(func)
    def wrapper(cls, *args, **kwargs):
        fun_name = func.__name__
        fun = ('_%s%s' % (cls.namespace, fun_name))
        if (not hasattr(cls, fun)):
            fun = ('_default%s' % fun_name)
        return getattr(cls, fun)(*args, **kwargs)
    return wrapper