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")