gistfile1.txt

bash-3.2$ io
Io 20090105
Io> respond_to := method( o, m, retv := true; e := try( o m ); e catch(Exception, if( e error containsSeq(" does not respond to "), retv = false)); retv)
==> method(o, m,
    retv := true; e := try(o m); e catch(Exception, if(e error containsSeq(" does not respond to "), retv = false)); retv
)
Io> O := Object clone
==>  O_0x100441870:
  type             = "O"

Io> O hello := method( "hello" println )
==> method(
    "hello" println
)
Io> O hello
hello
==> hello
Io> respond_to(O, hello)

  Exception: Object does not respond to 'hello'
  ---------
  Object hello                         Command Line 1
  Object respond_to                    Command Line 1

Io> respond_to(O, goodbye)

  Exception: Object does not respond to 'goodbye'
  ---------
  Object goodbye                       Command Line 1
  Object respond_to                    Command Line 1