human
Solve the following python programming problem given the following code:
def __call__(self, function) : 
    'Decorator function.  Adds an input/output cache to
        the specified function.' 
    from decorator import FunctionMaker 
    def decorator_apply(dec, func) : 
        'Decorate a function by preserving the signature even if dec
            is not a signature-preserving decorator.

            This recipe is derived from
            http://micheles.googlecode.com/hg/decorator/documentation.html#id14
            ' 
        return FunctionMaker.create (func, 'return decorated(%(signature)s)', dict (decorated = dec (func)), __wrapped__ = func) 
if (self.cachedir is not None) : 
        return decorator_apply (function.cache, function) 
else : 
        return function 

    
    

    Fix the buggy line: return decorator_apply (function.cache, function)
assistant
#Here is Python code to fix the buggy line: return decorator_apply (function.

return decorator_apply (self.cache, function)