r-ss?
r-ss?: string(word) -> boolean
.
True if the word contains either “r” or “ss”.
(check-expect (r-ss? "car") true)
(check-expect (r-ss? "ssnake") true)
(check-expect (r-ss? "wrassle") true)
(check-expect (r-ss? "confabulous") false)
no-7
no-7: number(n) -> number
Remove the 7s from a number.
(check-expect (no-7 127347) 1234)
(check-expect (no-7 7) 0)
abfx
abfx: string -> string
Change all but the first “x” to a “y”.
(check-expect (abfx "x") "x")
(check-expect (abfx "xx") "xy")
(check-expect (abfx "xxx") "xyy")
(check-expect (abfx "zxyxx") "zxyyy")