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child_processes = 3 
dead_processes = 0
# We fork 3 child processes. 
child_processes.times do
  fork do
    # They sleep for 3 seconds. 
    sleep 3
  end 
end

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fork do 
  5.times do
    sleep 1
    puts "I am an orphan!" 
  end
end

Process.wait
abort "Parent process died..."

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fork do 
  5.times do
    sleep 1
    puts "I'm an orphan!" 
  end
end
abort "Parent process died..."

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puts "parent process pid is #{Process.pid}"
if fork
  puts "entered the if block from #{Process.pid}"
else
  puts "entered the else block from #{Process.pid}"
end

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def tag_errors
  yield
rescue Exception => error
  error.extend(Lib::Error)
end

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t1 = Thread.new do
  raise RuntimeError, "oops!" rescue $!
end

t2 = Thread.new do
  raise ArgumentError, "doh!" rescue $!
end

puts "main: #{$!.inspect}"
puts "t1: #{t1.value.inspect}"

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module NoDoubleRaise
  def error_handled!
    $! = nil
  end
  
  def raise(*args)
    if $! && args.first != $!
      warn "Double raise at #{caller.first}, aborting"
      exit! false
    else

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[35] pry(main)> "  strinsg  ".strip
=> "strinsg"
[36] pry(main)> "  strinsg  ".squish
=> "strinsg"
[37] pry(main)> "  strin  sg  ".strip
=> "strin  sg"
[38] pry(main)> "  strin  sg  ".squish
=> "strin sg"

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# test is_a? and instance_of? methods
# instance_of? ignore the superclass


class SuperClass; end
class ChildClass < SuperClass ; end

b = ChildClass.new
puts b, b.instance_of?(SuperClass), b.is_a?(SuperClass)