Why does my postfix program in Python not work?

I have this code to calculate something given in postfix notation:

operator = ["+", "-", "*", "/", "^"]
operand=[]
exp=input("Please enter something in postfix notation:")
expression = exp.split(' ')
for ele in expression:
        if(ele not in operator):
            operand.append(ele)
        else:
            number1=eval(operand.pop())
            number2=eval(operand.pop())
        if(ele=="+"):
            answer=number2+number1
        elif(ele=="-"):
            answer=number2-number1
        elif(ele=="*"):
            answer=number2*number1
        elif(ele=="/"):
            answer=number2/number1
        elif(ele=="^"):
            answer=number2**number1
        operand.append(str(answer))
print("answer =", operand[0])

I can enter something to calculate but then it says NameError: name 'answer' is not defined and refers to the operand.append(str(answer)) line. How do I fix that and is the rest fine? Thank you for any help!

Your indentation isn't correct in your else block, which is appending garbage value for the answer at every element.

operator = ["+", "-", "*", "/", "^"]
operand=[]
exp=input("Please enter something in postfix notation:")
expression = exp.split(' ')

for ele in expression:
        if(ele not in operator):
            operand.append(ele)
        else:
            number1=eval(operand.pop())
            number2=eval(operand.pop())
            if(ele=="+"):
                answer=number2+number1
            elif(ele=="-"):
                answer=number2-number1
            elif(ele=="*"):
                answer=number2*number1
            elif(ele=="/"):
                answer=number2/number1
            elif(ele=="^"):
                answer=number2**number1
            operand.append(str(answer))

print("answer =", operand[0])

Here's your updated code.

Following is the output:

Please enter something in postfix notation:15 5 +
answer = 20