pro fib, nmax, char=char
;;; Check to see if keyword for characters is set.
if keyword_set(char) then begin
    current = char 			
    last = ''
endif else begin 
    current = 1
    last = 0
endelse
;;; print the first number
print, current
done = 0 ;we are not done
while ~done do begin ;While not done, do some stuff
    ;;; Create next number in the sequence
    new = current + last ; plus sign is for addition for numbers, 
                         ; concatonation for strings
    ;;; Swap variables
    last = current
    current = new
    ;;; test again to see if keyword is set
    if keyword_set(char) then begin
        ;;; If the length of the string is less than Nmax then print 
        ;;; else we are done
        if strlen(new) lt nmax then print, new else done = 1
    endif else begin
        ;;; If the latest number is less than Nmax then print else we
        ;;; are done
        if new lt nmax then print, new else done = 1
    endelse
endwhile

end