The way we ordinarily use +, it must have exactly two arguments: one on the left and one on the right. The flexibility of prefix notation means that, in Lisp, + can take any number of arguments, including none:
The way we ordinarily use +, it must have exactly two arguments: one on the left and one on the right. The flexibility of prefix notation means that, in Lisp, + can take any number of arguments, including none: