You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: variablize_keys.rb
    path of file: ./repos/facets/work/rejected/hash
    
    the code of the file until where you have to start completion: # DEPRECATED b/c of Hash#rekey and St
    
  def variablize_keys!(of_class=nil)
    raise ArgumentError, "Parameter must be a class" unless of_class.kind_of?(Class) if of_class
    if of_class
      self.each_key do |k|
        if k.respond_to?(:to_s) and k.class == of_class
          k = k.to_s
          nk = k[0,1] != '@' ? k : "@#{k}"
          self[nk]=self.delete(k)
        end
      end