r – what is the usage of see function(rx) here?

I am working in the string manipulation with the help of REGEX. I am going through some of the cheat-sheets. I noticed an example

”’ see <- function(rx) str_view_all(“abc ABC 123t.!?(){}n”, rx) ”’

What is the usage of function (rx) here ? I am curious to know the answer. Because if i remove function(rx) and give a pattern i get the same answer.

”’ see <- str_view_all(“abc ABC 123t.!?(){}n”, “a”) ”’

But here i have to use my variable to see my output. Can you please anyone explain?