human
Solve the following python programming problem given the following code:
def _subst_vars(path, local_vars) : 
    'In the string `path`, replace tokens like {some.thing} with the
    corresponding value from the map `local_vars`.

    If there is no corresponding value, leave the token unchanged.
    ' 
    def _replacer(matchobj) : 
        name = matchobj.group (1) 
        if (name in local_vars) : 
            return local_vars [name] 
else : 
            if (name in os.environ) : 
                return os.environ [name] 
return matchobj.group (0) 
return _VAR_REPL.sub (_replacer, _replacer) 

    
    

    Fix the buggy line: return _VAR_REPL.sub (_replacer, _replacer)
assistant
#Here is Python code to fix the buggy line: return _VAR_REPL.

return _VAR_REPL.sub (_replacer, path)