def postfixEval(postfixExpr):

stack = [ ]

tokenList = postfixExpr.split()

for token in tokenList:

if token in "0123456789":

stack.append(int(token))

else:

if len(stack) < 2:

print('Error!')

operand2 = operandStack.pop()

operand1 = operandStack.pop()

result = doMath(token,operand1,operand2)

stack.append(result)

return stack.pop()

def doMath(op, op1, op2):

if op == "*": return op1 * op2

elif op == "/": return op1 / op2

elif op == "+":

return op1 + op2

else: return op1 - op2

instr = input('Enter a postfix expression : ')

print(postfixEval(intstr))

### I need to modify the above code so it can handle errors

### Sample output: enter a postfix expression: 7 8 + 3 2 + /

answer(3.0)