停止无限循环的命令?？

Question

我正在开发一个图形界面，我希望有能力暂停或取消此文件后发送它。有三个按钮(发送，暂停和停止)，我已经完成了发送按钮的功能，我现在必须定义暂停和取消这两个按钮的功能，我该怎么办？下面是程序

def moh():


# Open grbl serial port
s = serial.Serial('/dev/ttyS0',115200)

# Open g-code file

f = open(file_path.get(), "r");

# Wake up grbl
s.write("\r\n\r\n".encode('utf8'))
time.sleep(2)   # Wait for grbl to initialize 
s.flushInput()  # Flush startup text in serial input

# Stream g-code to grbl
for line in f:
    l = line.strip() # Strip all EOL characters for consistency
    print ('Sending: ' + l)
    s.write((l + '\n').encode("utf8")) # Send g-code block to grbl
    grbl_out = s.readline().decode("utf8") # Wait for grbl response with carriage return
    print (' : ' + grbl_out)

# Wait here until grbl is finished to close serial port and file.
raw_input("  Press <Enter> to exit and disable grbl.") 

# Close file and serial port
f.close()
s.close()

b1= Button(Outil, text ="Send",background='White', command=moh)

感谢所有人