关于循环：python’或’不适用于while

python 'or' is not working with while

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print ('Welcome to Calculator')
a = int(input('Enter your first value'))
b = int(input('Enter your second value'))
print ('''Addition - type 1
Subtraction - type 2
Multiplication - type 3
Division - type 4''')
procedure = input('Enter a option')
while (procedure != '1') or (procedure != '2') or (procedure != '3') or (procedure != '4'):
procedure = input('Please choose the correct option')
def process ():
if procedure == '1':
print (a+b)
elif procedure == '2':
print(a-b)
elif procedure == '3':
print (a*b)
elif procedure == '4':
print (a/b)
else:
print('There is some error in code')
process ()

在这里，我希望每当过程的值不是1,2,3,4时，循环继续，但在此循环继续。请告诉错误如何正确执行