code: def resolve(self, current_file, rel_path):
      
      search_path = [path.dirname(current_file)] + self.search_path
  
      target_path = None
      for search in search_path:
        if self.exists(path.join(search, rel_path)):
          target_path = path.normpath(path.join(search, rel_path))
          break
  
      if not target_path:
        raise exceptions.EvaluationError('No such file: %r, searched %s' %
                              (rel_path, ':'.join(search_path)))
  
      return target_path, path.abspath(target_path)
docs: Search the filesystem.