RoR "goto" function?

What's the goto function for Ruby on Rails?
Something like this:
x: y
if z goto x

Obviously that's not the proper syntax, but I don't know what is. :(



    **** COMMODORE 64 BASIC V2 ****

 64K RAM SYSTEM  38911 BASIC BYTES FREE

READY.
10 PRINT GOTO(30)
LIST
10 PRINT GOTO(30)
READY.
RUN
?SYNTAX  ERROR IN 10
READY.
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