为什么会出现“未安装unrar”之类的错误？

Question

我已使用pip安装了unrar和rarfile，并且具有一组路径变量 C:\Users\username\AppData\Local\Programs\Python\Python37-32和C:\Users\username\AppData\Local\Programs\Python\Python37-32\Scripts。

每当我运行下面的代码，我就会得到error : unrar not installed

import rarfile, os, shutil, re

final_files = []

string_to_search = 'Contains given substring'

os.chdir(r'C:\Users\user\Desktop\PY\POC')

open_rar = rarfile.RarFile('PY.rar')

print(open_rar.namelist())

for n in open_rar.namelist():
    print(n)
    file_open = archive.open(n, 'r')
    text_in_files = file_open.readlines()
    print(string_to_search)
    print(text_in_files)