javascript – How to get around character filtering in XSS?

I solve XSS challenges. I have encountered difficulties in one that filters the "o" character in both uppercase and lowercase letters. I can run tag. I have to call the "prettyRobot" function to complete the challenge. But the character "o" is filtered, I try to run with

"eval (" prettyR "+" o "+" b "+" o "+" t () ")

But did not succeed. And fromCharCode can not be used because the "o" character is also included in the function fromCharCode.
How can I get around this?