AttributeError: 'str' object has no attribute 'sum'

This error message is raised when you try to call the `sum()` method on a string object, but strings do not have a `sum()` method.

For example, if you have a string variable `my_string` and you try to call `my_string.sum()`, you will get this error message.

To fix this error, you need to ensure that you are calling the `sum()` method on an iterable object like a list, tuple or set which supports this method.