Keyword arguments are function arguments that are passed by keyword, instead of position. Keyword arguments can be mixed with by-position arguments, and default-value expressions can be supplied for either kind of argument:
(define greet
(lambda (given #:last surname)
(string-append "Hello, " given " " surname)))
> (greet "John" #:last "Smith")
"Hello, John Smith"
> (greet #:last "Doe" "John")
"Hello, John Doe"
In above example last is a keyword argument.
