问为什么此方法的返回部分不起作用

EN

| stripChars |
stripChars := [ :string :chars |    
    str := string reject: [ :c | chars includes: c ].
    str displayNl.          "THIS WORKS."
    ^ str                   "THIS DOES NOT WORK."
].

newstr := stripChars 
    value: 'She was a soul stripper. She took my heart!'
    value: 'aei'.
newstr displayNl.

$ gst make_fn_ques.st
Sh ws  soul strppr. Sh took my hrt!
Object: 'Sh ws  soul strppr. Sh took my hrt!' error: return from a dead method context
SystemExceptions.BadReturn(Exception)>>signal (ExcHandling.st:254)
SystemExceptions.BadReturn class(Exception class)>>signal (ExcHandling.st:151)
String(Object)>>badReturnError (Object.st:1389)
UndefinedObject>>executeStatements (make_fn_ques.st:10)
nil