DEF FN upper case error

3 DEF FN u$(s$)=VAL$ "CHR$((CODE s$)-(32 AND CODE s$>96 AND CODE s$<124))+FN u$(s$(2 TO ))"( TO 28+12*(LEN s$>1))
106 LET a$="HeLlo"
107 LET a$=FN u$(a$)
200 PRINT "result:  ",a$


https://chuntey.wordpress.com/2010/01/07/adding-more-string-manipulation-techniques-to-basic/