code: def _find_module(mod_name):
      
      path = None
      for part in mod_name.split('.'):
          if path is not None:
              path = [path]
          file, path, description = imp.find_module(part, path)
          if file is not None:
              file.close()
      return path, description
docs: Iterate over each part instead of calling imp.find_module directly.
      This function is able to find submodules (e.g. sickit.tree)