def find_module(self, modname, folder=None):
        """Returns a resource corresponding to the given module

        returns None if it can not be found
        """
        for src in self.get_source_folders():
            module = _find_module_in_folder(src, modname)
            if module is not None:
                return module
        for src in self.get_python_path_folders():
            module = _find_module_in_folder(src, modname)
            if module is not None:
                return module
        if folder is not None:
            module = _find_module_in_folder(folder, modname)
            if module is not None:
                return module
        return None
Returns a resource corresponding to the given module

        returns None if it can not be found