define fibonacci as function
    taking n as integer
    and returning integer
    with body {
    if n is less than or equal to 1 then return n.
    return sum of
        call fibonacci with n as difference of n and 1, and
        call fibonacci with n as difference of n and 2.
}.

define x as integer with value of call fibonacci with n as 42.

import module io from standard-library.
call io:print with contents as string of x.