s = "Hello" s.slice!(0) #=> "ello"
尝试在一个irb：
ruby-1.9.3-p0 :001 > s = "Hello" => "Hello" ruby-1.9.3-p0 :002 > s.slice!(0) #=> "ello" => "H" ruby-1.9.3-p0 :003 > s => "ello"
