def source_file_name(self):
        """
        File name where the object is implemented (e.g. pandas/core/frame.py).
        """
        try:
            fname = inspect.getsourcefile(self.code_obj)
        except TypeError:
            # In some cases the object is something complex like a cython
            # object that can't be easily introspected. An it's better to
            # return the source code file of the object as None, than crash
            pass
        else:
            if fname:
                fname = os.path.relpath(fname, BASE_PATH)
                return fname