Dropping Down To The Metal™ (2018)

As much as we love Ruby, when you need to be really close to the metal, you have no choice but to use JavaScript. This is why I developed the javascript gem to help you harness the raw power of your machines. (https://github.com/chancancode/javascript)

In this talk, we will examine the Ruby tricks and black magic hidden behind this ludicrous invention. Along the way, we will learn about how Ruby internally deal with variable lookups, method calls, scoping and bindings. Together, we will push the limits of the Ruby language, taking it to places Matz never ever envisioned!

Transcript

1. Dropping
   Down To
   The Metal™
   ™
   

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2. View Slide

3. Java ☕
   

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4. Java ☕
   public class HelloWorld {
   public static void main(String[] args) {
   System.out.println("Hello world!");
   }
   }
   HelloWorld.java Terminal
   % javac HelloWorld.java
   % java HelloWorld
   Hello world!
   %
   %
   %
   

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5. Java ☕
   public class HelloWorld {
   public static void main(String[] args) {
   System.out.println("Hello world!");
   }
   }
   HelloWorld.java Terminal
   % mv HelloWorld.java hello.rb
   % ruby hello.rb
   ???
   %
   %
   %
   hello.rb
   $ It works™
   ) Syntax Error
   - Runtime Error
   

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6. Java ☕
   public class HelloWorld {
   public static void main(String[] args) {
   System.out.println("Hello world!”);
   }
   }
   HelloWorld.java
   Terminal
   hello.rb
   $ It works™
   ) Syntax Error
   - Runtime Error
   % ruby hello.rb
   hello.rb:2: syntax error, unexpected tIDENTIFIER, expecting ')'
   %
   %
   

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7. How Ruby Works J
   ???
   hello.rb Output
   Ruby Interpreter
   Compile Evaluate
   ???
   

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8. How Ruby Works J
   hello.rb Output
   Ruby Interpreter
   Compile Execute
   Syntax Error Runtime Error
   Parse
   

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9. How Ruby Works J
   I don’t speak Russian.
   NP
   N
   VP
   VP
   V N
   V
   I don’t speak Russian
   S
   $ All Good
   

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10. How Ruby Works J
    Don’t Russian I speak.
    V N V
    N
    I
    Don’t speak
    Russian
    K Syntax Error
    ???
    

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11. How Ruby Works J
    Russian doesn’t speak me.
    NP
    N
    VP
    VP
    V N
    V
    me
    doesn’t speak
    Russian
    S
    7 Semantic Error
    

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12. How Ruby Works J
    hello.rb Output
    Ruby Interpreter
    Compile Execute
    Syntax Error Runtime Error
    Parse
    

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13. How Ruby Works J
    public class HelloWorld {
    public static void main(String[] args) {
    System.out.println("Hello world!”);
    }
    }
    HelloWorld.java
    Terminal
    hello.rb
    $ It works™
    ) Syntax Error
    - Runtime Error
    % ruby hello.rb
    hello.rb:2: syntax error, unexpected tIDENTIFIER, expecting ')'
    %
    %
    

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14. JavaScript
    

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15. JavaScript ☕
    console.log("Hello world!");
    hello.js Terminal
    % node hello.js
    Hello world!
    %
    %
    

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16. console.log("Hello world!");
    hello.js Terminal
    % mv hello.js hello.rb
    % ruby hello.rb
    ???
    %
    %
    %
    $ It works™
    ) Syntax Error
    - Runtime Error
    hello.rb
    JavaScript ☕
    

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17. console.log("Hello world!");
    HelloWorld.java
    Terminal
    hello.rb
    $ It works™
    ) Syntax Error
    - Runtime Error
    JavaScript ☕
    % ruby hello.rb
    hello.js:1:in `': undefined local variable or method `console’ for main:Object (NameError)
    %
    %
    

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18. console.log("Hello world!");
    JavaScript ☕
    

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19. console.log("Hello world!");
    Local variable or method named “console”
    JavaScript ☕
    

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20. console.log("Hello world!");
    JavaScript ☕
    Call the instance method “log” on “console”
    

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21. console.log("Hello world!");
    JavaScript ☕
    Optional parenthesis
    

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22. console.log("Hello world!");
    JavaScript ☕
    Method argument (string literal “Hello world!”)
    

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23. console.log("Hello world!");
    JavaScript ☕
    Optional semicolon
    

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24. console.log("Hello world!");
    JavaScript ☕
    

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25. console.log("Hello world!");
    HelloWorld.java
    Terminal
    % ruby hello.rb
    hello.js:1:in `': undefined local variable or method `console’ for main:Object (NameError)
    %
    %
    hello.rb
    JavaScript ☕
    

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26. class Console
    def log(*args)
    puts(*args)
    end
    end
    console = Console.new
    # Begin "JavaScript"
    console.log("Hello world!");
    HelloWorld.java
    hello.rb
    JavaScript ☕
    Terminal
    % ruby hello.rb
    Hello world!
    %
    %
    

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27. View Slide

28. class Console
    def log(*args)
    puts(*args)
    end
    end
    console = Console.new
    # Begin "JavaScript"
    console.log("Hello world!");
    HelloWorld.java
    hello.rb
    JavaScript ☕
    Terminal
    % ruby hello.rb
    Hello world!
    %
    %
    class Console
    def log(*args)
    puts(*args)
    end
    end
    console = Console.new
    L
    

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29. require "javascript"
    javascript do
    console.log("Hello world!");
    end
    HelloWorld.java
    hello.rb
    JavaScript ☕
    Terminal
    % ruby hello.rb
    Hello world!
    %
    %
    

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30. DSL
    Domain-specific Language
    M
    

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31. def javascript
    yield
    end
    HelloWorld.java
    javascript.rb
    require "javascript"
    javascript do
    console.log("Hello world!");
    end
    hello.rb
    DSL M
    Terminal
    % ruby hello.rb
    hello.rb:4:in `block in ': undefined local variable or method `console' for main:Object (NameError)
    %
    %
    

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32. class Console
    def log(*args)
    puts(*args)
    end
    end
    def console
    Console.new
    end
    def javascript
    yield
    end
    HelloWorld.java
    javascript.rb
    require "javascript"
    javascript do
    console.log("Hello world!");
    end
    hello.rb
    DSL M
    Terminal
    % ruby hello.rb
    Hello world!
    %
    %
    

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33. class Console
    def log(*args)
    puts(*args)
    end
    end
    def console
    Console.new
    end
    def javascript
    yield
    end
    HelloWorld.java
    javascript.rb
    require "javascript"
    javascript do
    console.log("Hello world!");
    end
    console.log("Hello world!");
    hello.rb
    DSL M
    Terminal
    % ruby hello.rb
    Hello world!
    Hello world!
    %
    %
    L
    

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34. def javascript
    yield
    end
    HelloWorld.java
    javascript.rb
    require "javascript"
    javascript do
    self.console.log("Hello world");
    end
    hello.rb
    DSL M
    Terminal
    % ruby hello.rb
    hello.rb:4:in `block in ': undefined local variable or method `console' for main:Object (NameError)
    %
    %
    Instance of Object
    

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35. class Console ... end
    class JavaScript
    def console
    Console.new
    end
    end
    def javascript(&block)
    JavaScript.new.instance_exec(&block)
    end
    HelloWorld.java
    javascript.rb
    require "javascript"
    javascript do
    console.log("Hello world!");
    end
    console.log("Hello world!");
    hello.rb
    DSL M
    Terminal
    % ruby hello.rb
    Hello world!
    hello.rb:4:in `block in ': undefined local variable or method `console' for main:Object (NameError)
    %
    %
    N
    self is instance of JavaScript
    O
    self is instance of Object
    

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36. class Console ... end
    class JavaScript
    def console
    Console.new
    end
    end
    def javascript(&block)
    JavaScript.new.instance_exec(&block)
    end
    HelloWorld.java
    javascript.rb
    require "javascript"
    javascript do
    console.log("Hello world!");
    end
    hello.rb
    DSL M
    Terminal
    % ruby hello.rb
    Hello world!
    %
    %
    

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37. View Slide

38. Variables ℹ
    

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39. require "javascript"
    javascript do
    let message = "Hello world!";
    console.log(message);
    end
    hello.rb Terminal
    $ It works™
    ) Syntax Error
    - No Method Error
    ( Name Error
    % ruby hello.rb
    ???
    %
    %
    Variables ℹ
    

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40. $ It works™
    ) Syntax Error
    - No Method Error
    ( Name Error
    console.log("Hello world!");
    hello.rb
    Terminal
    Variables ℹ
    % ruby hello.rb
    hello.rb:4:in `block in ': undefined method `let' for # (NoMethodError)
    %
    %
    

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41. let message = "Hello world!";
    Variables ℹ
    

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42. let(message = "Hello world!");
    Variables ℹ
    

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43. let(message = "Hello world!");
    Variables ℹ
    Call the method named “let”…
    

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44. let(message = "Hello world!");
    Variables ℹ
    …with this argument.
    

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45. let(message = "Hello world!");
    Variables ℹ
    What is it?
    

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46. let(message = "Hello world!");
    Variables ℹ
    Assignment Expression
    

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47. let(message = "Hello world!");
    Variables ℹ
    

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48. let(message = "Hello world!");
    Variables ℹ
    

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49. message = "Hello world!";
    let(message);
    Variables ℹ
    

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50. message = "Hello world!";
    let("Hello world!");
    Variables ℹ
    

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51. class Console ... end
    class JavaScript
    def console ... end
    def let(???)
    ???
    end
    end
    def javascript ... end
    HelloWorld.java
    javascript.rb
    require "javascript"
    javascript do
    let message = "Hello world!";
    console.log(message);
    end
    hello.rb
    Terminal
    %
    Variables ℹ
    

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52. message = "Hello world!";
    let("Hello world!");
    Variables ℹ
    $
    Q
    

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53. class Console ... end
    class JavaScript
    def console ... end
    def let(*)
    # ¯\_(ϑ)_/¯
    end
    end
    def javascript ... end
    HelloWorld.java
    javascript.rb
    require "javascript"
    javascript do
    let message = "Hello world!";
    console.log(message);
    end
    hello.rb
    Terminal
    % ruby hello.rb
    Hello world!
    %
    %
    Variables ℹ
    

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54. View Slide

55. wait a second… J
    

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56. require "javascript"
    javascript do
    let message;
    message = "Hello world!";
    console.log(message);
    end
    hello.rb Terminal
    $ It works™
    ) Syntax Error
    - No Method Error
    ( Name Error
    % ruby hello.rb
    ???
    %
    %
    Variables ℹ
    

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57. $ It works™
    ) Syntax Error
    - No Method Error
    ( Name Error
    console.log("Hello world!");
    hello.rb
    Terminal
    Variables ℹ
    % ruby hello.rb
    hello.rb:4:in `block in ': undefined method `message’ for # (NoMethodError)
    %
    %
    

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58. let message;
    message = "Hello world!";
    console.log(message);
    Variables ℹ
    

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59. let(message);
    message = "Hello world!";
    console.log(message);
    Variables ℹ
    

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60. let(message);
    message = "Hello world!";
    console.log(message);
    Variables ℹ
    defined here
    

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61. let(message);
    message = "Hello world!";
    console.log(message);
    Variables ℹ
    not local variable
    

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62. let(message);
    message = "Hello world!";
    console.log(message);
    Variables ℹ
    method?
    

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63. let(message());
    message = "Hello world!";
    console.log(message);
    Variables ℹ
    

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64. class Console ... end
    class JavaScript
    def console ... end
    def let ... end
    def message
    # ¯\_(ϑ)_/¯
    end
    end
    def javascript ... end
    HelloWorld.java
    javascript.rb
    Terminal
    % ruby hello.rb
    Hello world!
    %
    %
    Variables ℹ
    require "javascript"
    javascript do
    let message;
    message = "Hello world!";
    console.log(message);
    end
    hello.rb
    

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65. class Console ... end
    class JavaScript
    def console ... end
    def let ... end
    def message
    # ¯\_(ϑ)_/¯
    end
    end
    def javascript ... end
    HelloWorld.java
    javascript.rb
    Terminal
    % ruby hello.rb
    Hello world!
    %
    %
    Variables ℹ
    def message
    # ¯\_(ϑ)_/¯
    end
    L
    require "javascript"
    javascript do
    let message;
    message = "Hello world!";
    console.log(message);
    end
    hello.rb
    

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66. class Console ... end
    class JavaScript
    def console ... end
    def let ... end
    def method_missing(*)
    # ¯\_(ϑ)_/¯
    end
    end
    def javascript ... end
    HelloWorld.java
    javascript.rb
    require "javascript"
    javascript do
    let message;
    message = "Hello world!";
    console.log(message);
    end
    hello.rb
    Terminal
    % ruby hello.rb
    Hello world!
    %
    %
    Variables ℹ
    

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67. View Slide

68. Functions ⤵
    

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69. require "javascript"
    javascript do
    function hello() {
    console.log("Hello world!");
    }
    hello();
    end
    hello.rb Terminal
    $ It works™
    ) Syntax Error
    - No Method Error
    ( Name Error
    % ruby hello.rb
    ???
    %
    %
    Functions ⤵
    

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70. require "javascript"
    javascript do
    function hello() {
    console.log("Hello world!");
    }
    hello();
    end
    hello.rb Terminal
    $ It works™
    ) Syntax Error
    - No Method Error
    ( Name Error
    % ruby hello.rb
    ???
    %
    %
    Functions ⤵
    

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71. $ It works™
    ) Syntax Error
    - No Method Error
    ( Name Error
    console.log("Hello world!");
    hello.rb
    Terminal
    % ruby hello.rb
    %
    %
    * None of the above
    Functions ⤵
    

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72. function hello() {
    console.log("Hello world!");
    }
    hello();
    Functions ⤵
    

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73. function(hello() {
    console.log("Hello world!");
    });
    hello();
    Functions ⤵
    

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74. function(hello() {
    console.log("Hello world!");
    });
    hello();
    Call the method named “function”…
    Functions ⤵
    

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75. function(hello() {
    console.log("Hello world!");
    });
    hello();
    …with this argument.
    Functions ⤵
    

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76. function(hello() {
    console.log("Hello world!");
    });
    hello();
    What is it?
    Functions ⤵
    

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77. function(hello() {
    console.log("Hello world!");
    });
    hello();
    Call the method named “hello”…
    Functions ⤵
    

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78. function(hello() {
    console.log("Hello world!");
    });
    hello();
    …but what is this?
    Functions ⤵
    

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79. function(hello() {
    console.log("Hello world!");
    });
    hello();
    A block argument to the “hello” method.
    Functions ⤵
    

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80. function(hello() {
    console.log("Hello world!");
    });
    hello();
    Call the method named “hello”.
    Functions ⤵
    

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81. function(hello() {
    console.log("Hello world!");
    });
    hello();
    Undefined methods!
    Functions ⤵
    

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82. class Console ... end
    class JavaScript
    def console ... end
    def let ... end
    def method_missing(*)
    # ¯\_(ϑ)_/¯
    end
    end
    def javascript ... end
    HelloWorld.java
    javascript.rb
    require "javascript"
    javascript do
    function hello() {
    console.log("Hello world!");
    }
    hello();
    end
    hello.rb
    Terminal
    %
    Functions ⤵
    

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83. class Console ... end
    class JavaScript
    def ... end
    def function(*); end
    def method_missing(name, *, &block)
    if block_given?
    define_singleton_method(name, block)
    end
    end
    end
    def javascript ... end
    HelloWorld.java
    javascript.rb
    require "javascript"
    javascript do
    function hello() {
    console.log("Hello world!");
    }
    hello();
    end
    hello.rb
    Terminal
    Functions ⤵
    % ruby hello.rb
    Hello world!
    %
    %
    

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84. View Slide

85. Arguments S
    

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86. require "javascript"
    javascript do
    function hello(name) {
    console.log(`Hello ${name}!`);
    }
    hello("world");
    end
    hello.rb Terminal
    $ It works™
    ) Syntax Error
    - No Method Error
    ( Name Error
    % ruby hello.rb
    ???
    %
    %
    Arguments S
    Arguments
    

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87. require "javascript"
    javascript do
    function hello(name) {
    console.log(`Hello ${name}!`);
    }
    hello("world");
    end
    hello.rb Terminal
    $ It works™
    ) Syntax Error
    - No Method Error
    ( Name Error
    % ruby hello.rb
    ???
    %
    %
    Arguments S
    Arguments
    

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88. View Slide

89. gem install javascript
    

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90. chancancode/javascript
    

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91. View Slide

92. View Slide

93. Why? T
    

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94. class Post < ActiveRecord::Base
    before_create &javascript {
    function(post) {
    console.log(`Created ${post.title}`);
    }
    }
    end
    app/models/post.rb
    Why? T
    

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95. Why not? U
    

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96. Godfrey Chan
    @chancancode
    

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