I have a string `sentence` that contains trailing punctuation that I want to remove. To do this I'm passing a string parameter `punctuation` to my function `remove_punc` that contains the trailing punctuation that I want to remove:

```
def remove_punc(sentence, punctuation):
   """takes input parameters sentence (type string) and 
   punctuation (type string), and returns a string that 
   strips all trailing punctuations in sentence."""

```

I have tried `sentence.rstrip(punctuation)` for the example:

```
remove_punc("This is some, and \"I\" know it is a long one!", "?!.,")

```

However this returns:

```
'This is some, and "I" know it is a long one'

```

The expected output is:

```
'This is some and "I" know it is a long one'

```

Am I using `rstrip()` incorrectly?