$ irb
irb(main):001:0> stop_words = %w{the a and if}
=> ["the", "a", "and", "if"]
irb(main):002:0> stop_words.each{|x| stop_words << x.capitalize}
^CIRB::Abort: abort then interrupt!
        from (irb):2:in `call'
        from (irb):2:in `block in irb_binding'
        from (irb):2:in `each'
        from (irb):2
        from /usr/bin/irb:12:in `<main>'
irb(main):003:0> stop_words.each{|x| stop_words << x.capitalize}
^CIRB::Abort: abort then interrupt!
        from (irb):3:in `call'
        from (irb):3:in `block in irb_binding'
        from (irb):3:in `each'
        from (irb):3
        from /usr/bin/irb:12:in `<main>'
irb(main):004:0> stop_words.each{|x| stop_words << x.capitalize}
^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C
quit
quit
end
end
^C^C^C
kill
die!
quit
^Z
[1]+  Stopped                 irb
$ ps
  PID TTY          TIME CMD
 5008 pts/0    00:00:00 bash
15672 pts/0    00:00:33 irb
15707 pts/0    00:00:00 ps
$ kill 15672
$ ps
  PID TTY          TIME CMD
 5008 pts/0    00:00:00 bash
15672 pts/0    00:00:33 irb
15714 pts/0    00:00:00 ps
$ kill -9 15672
$ ps
  PID TTY          TIME CMD
 5008 pts/0    00:00:00 bash
15717 pts/0    00:00:00 ps
[1]+  Killed                  irb
$