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: predefined_spec.rb
    path of file: ./repos/ferrocarril/spec-runner/spec/ruby/language
    
    the code of the file until where you have to start completion: require_relative '../spec_helper'
require 'stringio'

# The following tables are excerpted from Programming Ruby: The Pragmatic Programmer's Guide'
# Second Edition by Dave Thomas, Chad Fowler, and Andy Hunt, page 319-22.
#
# Entries marked [r/o] are read-only and an error will be raised of the program attempts to
# modify them. Entries marked [thread] are thread local.

=begin
Exception Info
    
    def obj.foo; yield; end
    def obj.foo2; yield; end

    stdin = StringIO.new("foo\nbar\nbaz\nqux\n", "r")
    match = stdin.gets

    obj.foo { match = stdin.gets }

    match.should == "bar\n"
    $_.should == match

    eval 'match = stdin.gets'

    match.should == "baz\n"
    $_.should == match

    obj.foo2 { match = stdin.gets }

    match.should == "qux\n"
    $_.should == match
  end

  it "is Thread-local" do
    $_ = nil
    running = false

    thr = Thread.new do
      $_ = "last line"
      running = true
    end

    Thread.pass until running
    $_.should be_nil

    thr.join
  end

  it "can be assigned any value" do
    $_ = nil
    $_.should == nil
    $_ = "foo"
    $_.should == "foo"
    o = Object.new
    $_ = o
    $_.should == o
    $_ = 1
    $_.should == 1
  end
end