为什么'tm'不能作为if语句的变量注册？

Question

run = 1 
list1 = [] 
for i in range(2): 
    while run > 0 : 
      print("-------------------------------------------------------") 
      run = 1 
      reg_num = input("Registration Number in caps: ") 
      tsh = int(input("Hour Entered : ")) 
      tsm = int(input("Minute Entered : ")) 
      tss = int(input("Second Entered : ")) 
      print("") 
      teh = int(input("Hour Exited : ")) 
      tem = int(input("Minute Exited : ")) 
      tes = int(input("Second Exited : ")) 
      print("Time Entered (camera1)", tsh, ":", tsm, ":", tss, "and Time Exited (camera2)", teh, ":", tem, ":", tes) 
      if tsh < teh: 
       tm = (((teh - tsh)*60) + (tem - tsm) +((tes - tss)/60))/60 
      elif tsh > teh: 
       teh = 24 + teh 
       tm = (((teh - tsh)*60) + (tem - tsm) +((tes - tss)/60))/60 
      speed = run/tm 
      print("speed of", reg_num, "is", "{:.2f}".format(speed), "mph") 
      if speed > 70: 
       list1.append(reg_num)    
      break 
print("Overspeeding vehicles are: ") 
for item in list1: 
    print (item) 

这是计算通过相隔1英里的速度摄像头的车辆速度的代码。我必须列出超过限速的车辆列表。问题是代码计算速度（速度=运行/时间）错误消息说明“tm”（总分钟）没有被定义。你能修改一下，告诉我什么是错的。

Answer 1

问题是你的条件在'if'语句没有满足。

if tsh = teh: 
    tm = bla 
elif tsh < teh: 
    tm = bla * 2 
else: 
    tm = bla/2 # Add the 'else' part to do something when all else fails.