我无法在变量中存储全局变量

我有3个python文件:

main.py

import shell
import basic

if __name__ == "__main__":
    shell.init()

shell.py

import main

def init():
    while True:
        global command
        command = input("")
        main.basic.interpreter()

if __name__ == "__main__":
    init()

和basic.py

import main

com = main.shell.command

def interpreter():
    return com

When I run main.py it runs shell.py which asks for user input and then stores it in a global variable and calls the interpreter function that returns the com varibale. But when I run it I get an error: module 'shell' has no attribute 'command', and when I tested it again I got: partially initialized module 'shell' has no attribute 'command' (most likely due to a circular import).

but when I remove the com variable and instead returning the main.shell.command (return main.shell.command) it works.

有没有办法将其存储为变量,是什么引起了问题? 我不明白怎么了