im working on a pylint test for my basic calculator and i and one pylint error left which says. 'Either all return statements in a function should return an expression, or none of them should.$\text{'}$ and i cant seem to fix it ive been at it for an hour

this is my code:

$\text{'}\text{'}\text{'}$making a calculator that output add$/$sub$/$mul$/$div$\text{'}\text{'}\text{'}$

def calculator$($num$1,$ operator, num$2)$:

$\text{'}\text{'}\text{'}$Perform a calculation based on two numbers and a given operator.$\text{'}\text{'}\text{'}$

try:

num$1=$ float$($num$1)$

num$2=$ float$($num$2)$

if operator $==\text{'}+\text{'}$:

return num$1+$ num$2$

if operator $==\text{'}-\text{'}$:

return num$1-$ num$2$

if operator $==\text{'}*\text{'}$:

return num$1*$ num$2$

if operator $==\text{'}/\text{'}$:

if num$2!=0$:

return num$1/$ num$2$

return "Cannot divide by zero"

except ValueError:

return "Invalid input"