予約語
予約語でも、メソッドであることが明らかならメソッドにできます。
class Rubyco def BEGIN; self; end def class; self; end def ensure; self; end def nil; self; end def self; self; end def when; self; end def END; self; end def def; self; end def false; self; end def not; self; end def super; self; end def while; self; end def alias; self; end def defined?; self; end def for; self; end def or; self; end def then; self; end def yield; self; end def and; self; end def do; self; end def if; self; end def redo; self; end def true; self; end def begin; self; end def else; self; end def in; self; end def rescue; self; end def undef; self; end def break; self; end def elsif; self; end def module; self; end def retry; self; end def unless; self; end def case; self; end def end; self; end def next; self; end def return; self; end def until; self; end end p Rubyco.new.BEGIN.class.ensure.nil.self.when.END.def.false.not.super.while.alias.defined?.for.or.then.yield.and.do.if.redo.true.begin.else.in.rescue.undef.break.elsif.module.retry.unless.case.end.next.return.until #=> #<Rubyco:0x298c350>