human
Solve the following python programming problem given the following code:
@ extensionclassmethod (Observable) 
def from_callback(cls, func, selector = None) : 
    'Converts a callback function to an observable sequence.

    Keyword arguments:
    func -- {Function} Function with a callback as the last parameter to
        convert to an Observable sequence.
    selector -- {Function} [Optional] A selector which takes the arguments
        from the callback to produce a single item to yield on next.

    Returns {Function} A function, when executed with the required
    parameters minus the callback, produces an Observable sequence with a
    single value of the arguments to the callback as a list.
    ' 
    def function(* args) : 
        arguments = list (args) 
        def subscribe(observer) : 
            def handler(* args) : 
                results = list (args) 
                if selector : 
                    try : 
                        results = selector (args) 
except Exception as err : 
                        observer.on_error (err) 
                        return 
observer.on_next (results) 
else : 
                    if (isinstance (results, list) and (len (results) <= 1)) : 
                        observer.on_next (* results) 
else : 
                        observer.on_next (results) 
observer.on_completed () 
arguments.append (handler) 
            func (* arguments) 
return AnonymousObservable (subscribe) 
return selector 

    
    

    Fix the buggy line: return selector
assistant
#Here is Python program to fix the buggy line: return selector
.

return def function(