is it possible to create an object by its name in the run time

[Yang Zhang]

 Hi all,
        I wonder if it is possible to create an object of func, class or
 method in the run time by it's name? To make it more clear, let me show
 you an example: I parsed the python code and found a function with name
'len'.
 I want to know if it is a build-in func(where can I look up?). If so,
ignore
 it otherwise I want to find out which module is it defined in. All I know
 is the name (which is a string), and all the modules that this program have
 imported. In the same way, I also need to process the class and methods
 call. I wonder if it is possible? I will appreciate your help very much!!

-Ryan