100 PROGRAM "Fibonacc.bas"
110 FOR I=0 TO 10
120   PRINT FIB(I);
130 NEXT
140 DEF FIB(K)
150   SELECT CASE K
160   CASE IS<0
170     PRINT "Negative parameter to Fibonacci.":STOP
180   CASE 0
190     LET FIB=0
200   CASE 1
210     LET FIB=1
220   CASE ELSE
230     LET FIB=FIB(K-1)+FIB(K-2)
240   END SELECT
250 END DEF