SUB IsEmpty(s$)
    IF Len(s$) = 0 THEN
       PRINT "String is empty"
    ELSE
       PRINT "String is not empty"
    END IF
    IF s$ = "" THEN PRINT "yes, the string is empty"
    IF s$ <> "" THEN PRINT "no, the string is not empty"
END SUB

LET t$ = ""
CALL IsEmpty(t$)
LET u$ = "not empty"
CALL IsEmpty(u$)
END