Make Up Your Own "Hello, World!"

We all love Ruby. Maybe we’ve only been paid to write code in Ruby (and maybe JavaScript). But there are so many other languages out there, and they all have strengths, weaknesses, and very different communities surrounding them.
Let’s talk about language exploration. We’ll discuss how to learn a new language, considerations when introducing things to production, and come up with some ideas for Ruby and it’s ecosystem. Plan on dipping your toes in Elixir, Go, Haskell, Rust, and Scala during the session.

Transcript

1. Make up your own
   "Hello, World!"
   @justincampbell
   

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2. Learn (verb)
   4 gain or acquire knowledge of or skill in (something)
   by study, experience, or being taught
   4 commit to memory
   4 become aware of (something) by information or
   from observation
   

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5. How?
   

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8. You need a project
   

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9. I need a project
   

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10. HTTP
    

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11. Writes
    

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12. State
    

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13. Testing
    

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14. TDD
    

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15. TDD
    

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16. Goals
    4 HTTP
    4 Writes
    4 Shared State
    4 TDD
    

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17. 4 Billboard
    4 Blog
    4 Chat
    4 Counter
    4 Dice
    4 Stats
    4 Storage
    4 Twitter
    4 URL Shortener
    

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18. URL
    Shortener
    

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19. Shorten
    POST / "url=http://justincampbell.me" -------> ,---------,
    |Shortener|
    201 Created /1
    

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20. Expand
    GET /1 --------------------------------------> ,---------,
    |Shortener|
    301 Redirect Location: http://justincampbell.me
    

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21. Missing
    GET /54321 ----------------------------------> ,---------,
    |Shortener|
    404 Not Found

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22. Ruby
    

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23. # Ruby
    post '/' do
    token = shortener.shorten(params[:url])
    [201, "/#{token}"]
    end
    

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24. # Ruby
    post '/' do
    token = shortener.shorten(params[:url])
    [201, "/#{token}"]
    end
    get '/:token' do |token|
    full_url = shortener.expand(token)
    halt 404 unless full_url
    redirect full_url
    end
    

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25. # Ruby
    class Shortener
    def shorten(url)
    token = id_generator.next.to_s
    urls[token] = url
    token
    end
    def expand(token)
    urls[token]
    end
    end
    

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26. # Ruby
    class Shortener
    def id_generator
    @id_generator ||= (1..Float::INFINITY).enum_for
    end
    def urls
    @urls ||= Hash.new
    end
    end
    

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27. # Ruby
    def shortener
    Shortener.instance
    end
    class Shortener
    def self.instance
    @instance ||= new
    end
    end
    

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28. Thread-Safe?
    

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30. Clojure
    

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31. ; Clojure
    (def token
    (atom 0))
    

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32. ; Clojure
    (def token
    (atom 0))
    (defn next-token []
    (swap! token inc))
    

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33. ; Clojure
    (def token
    (atom 0))
    (defn next-token []
    (swap! token inc))
    (next-token) ; => 1
    

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34. ; Clojure
    (def token
    (atom 0))
    (defn next-token []
    (swap! token inc))
    (next-token) ; => 1
    (next-token) ; => 2
    

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36. # Ruby
    def shorten(url)
    token = id_generator.next.to_s
    urls[token] = url
    token
    end
    

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37. # Ruby
    def shorten(url)
    token = id_generator.next.to_s
    urls[token] = url
    token
    end
    {- Haskell -}
    shorten :: Url -> Token
    

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38. # Ruby
    def shorten(url)
    token = id_generator.next.to_s
    urls[token] = url
    token
    end
    {- Haskell -}
    shorten :: Url -> Token
    {- shorten is a function from a Url to a Token -}
    

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39. # Ruby
    def shorten(url)
    token = id_generator.next.to_s
    urls[token] = url
    token
    end
    {- Haskell -}
    type Token = String
    type Url = String
    shorten :: Url -> Token
    

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40. # Ruby
    def shorten(url)
    token = id_generator.next.to_s
    urls[token] = url
    token
    end
    {- Haskell -}
    type Token = String
    type Url = String
    shorten :: Url -> Token
    shorten url = token where
    {- increment token, store url -}
    

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41. {- Haskell -}
    type Token = String
    type Url = String
    shorten :: Url -> Token
    

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42. {- Haskell -}
    type Token = String
    type Url = String
    shorten :: Url -> World -> Token
    

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43. {- Haskell -}
    type Token = String
    type Url = String
    shorten :: Url -> World -> World
    

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44. {- Haskell -}
    type Token = String
    type Url = String
    data World = World { id :: Int,
    urls :: Map Token Url }
    shorten :: Url -> World -> World
    

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45. {- Haskell -}
    type Token = String
    type Url = String
    data World = World { id :: Int,
    urls :: Map Token Url }
    shorten :: Url -> World -> World
    shorten url world = newWorld where
    nextId = succ $ _id world
    token = show nextId
    newUrls = insert token url $ _urls world
    newWorld = World nextId newUrls
    

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46. {- Haskell -}
    type Token = String
    type Url = String
    data World = World { id :: Int,
    urls :: Map Token Url }
    shorten :: Url -> World -> World
    

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47. {- Haskell -}
    type Token = String
    type Url = String
    data World = World { id :: Int,
    urls :: Map Token Url }
    shorten :: Url -> World -> World
    expand :: Token -> World -> Maybe Url
    

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48. Nim
    

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49. # Nim
    type Token = string
    type Url = string
    var id = 0
    var urls = newTable[Token, Url]()
    proc shorten*(url: Url): Token =
    id += 1
    let token = intToStr(id)
    urls[token] = url
    return token
    proc expand*(token: Token): Url =
    if hasKey(urls, token):
    return urls[token]
    

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50. {- Haskell -}
    expand :: Token -> World -> Maybe Url
    # Nim
    proc expand*(token: Token): Url =
    # ...
    

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51. # Nim
    proc expand*(token: Token): Url =
    # ...
    

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52. # Nim
    proc expand*(token: Token): Url =
    # ...
    shorten("google.com") # => "1"
    

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53. # Nim
    proc expand*(token: Token): Url =
    # ...
    shorten("google.com") # => "1"
    expand("1") # => "google.com"
    

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54. # Nim
    proc expand*(token: Token): Url =
    # ...
    shorten("google.com") # => "1"
    expand("1") # => "google.com"
    expand("54321") # => nil
    

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56. nil
    

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57. NoMethodError: undefined method `name' for nil:NilClass
    

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58. NoMethodError: undefined method `name' for nil:NilClass
    Type Error
    

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59. Go
    

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60. // Go
    url, err := shortener.expand(token);
    if err != nil {
    http.NotFound(response, request);
    }
    http.Redirect(response, request, url, 301);
    

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61. // Go
    url, err := shortener.expand(token);
    // if err != nil {
    // http.NotFound(response, request);
    // }
    http.Redirect(response, request, url, 301);
    

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62. // Go
    url, err := shortener.expand(token);
    // if err != nil {
    // http.NotFound(response, request);
    // }
    http.Redirect(response, request, url, 301); // ???
    

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63. In two weeks, Im headed to
    India to give a keynote at a
    Go Conference. Last year
    this time, I was like, "why
    do I need a GOROOT and
    GOPATH?" - Bryan Lyles
    

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64. # Ruby
    get '/:token' do |token|
    url = shortener.expand(token)
    halt 404 unless url
    redirect url
    end
    

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65. # Ruby
    get '/:token' do |token|
    begin
    url = shortener.expand(token)
    redirect url
    rescue # ???
    halt 404
    end
    end
    

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66. Elixir/Erlang
    

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67. # Elixir
    {:ok, url} = Shortener.Core.expand(conn.params[:token])
    

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68. # Elixir
    {:ok, url} = Shortener.Core.expand(conn.params[:token])
    # ** (MatchError) no match of right hand side value:
    # {:error, "Token not found"}
    

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69. # Elixir
    case Shortener.Core.expand(conn.params[:token]) do
    {:ok, url} -> redirect conn, to: url
    _ -> conn.send 404, "Not found"
    end
    

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70. # Ruby
    case url = shortener.expand(token)
    when String
    redirect url
    when NilClass
    halt 404
    end
    

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71. # Ruby
    case result = shortener.expand(token)
    when result.success?
    redirect result.value
    else
    halt 404
    end
    

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72. # Ruby
    def halve(number)
    number / 2.0
    end
    halve 5 # => 2.5
    halve "5" # strings don't respond to `/`
    

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76. Embrace
    Conventions
    

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78. " Clojure
    Plug 'guns/vim-clojure-static'
    Plug 'guns/vim-sexp'
    Plug 'tpope/vim-classpath'
    Plug 'tpope/vim-fireplace'
    Plug 'tpope/vim-leiningen'
    Plug 'tpope/vim-sexp-mappings-for-regular-people'
    " CoffeeScript
    Plug 'kchmck/vim-coffee-script'
    " Elixir
    Plug 'elixir-lang/vim-elixir'
    " Go
    Plug 'fatih/vim-go'
    " Haskell
    Plug 'dag/vim2hs'
    Plug 'eagletmt/ghcmod-vim'
    Plug 'shougo/vimproc.vim'
    " JavaScript
    Plug 'pangloss/vim-javascript'
    " Nim
    Plug 'zah/nimrod.vim'
    

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79. " OCaml
    Plug 'ocamlpro/ocp-indent'
    Plug 'the-lambda-church/merlin'
    " PureScript
    Plug 'raichoo/purescript-vim'
    " Ruby
    Plug 'ecomba/vim-ruby-refactoring'
    Plug 'hwartig/vim-seeing-is-believing'
    Plug 'jgdavey/vim-blockle'
    Plug 'tpope/vim-rails'
    Plug 'tpope/vim-rake'
    Plug 'vim-ruby/vim-ruby'
    " Rust
    Plug 'wting/rust.vim'
    " Scala
    Plug 'derekwyatt/vim-scala'
    " Shell
    Plug 'markcornick/vim-bats'
    Plug 'rosstimson/bats.vim'
    " Thrift
    Plug 'solarnz/thrift.vim'
    

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80. make
    

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81. make
    default: deps test
    deps:
    which bundle || gem install bundler
    bundle check || bundle install
    test:
    bundle exec rspec spec/
    

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82. Why?
    

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83. New Perspective
    

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84. "If you do what you've
    always done, you'll get
    what you've always
    gotten"
    - Henry Ford
    

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85. Language
    Matters
    

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86. The principle of linguistic relativity
    holds that the structure of a language
    affects the ways in which its respective
    speakers conceptualize their world, i.e.
    their world view, or otherwise
    influences their cognitive processes.
    http://en.wikipedia.org/wiki/Linguistic_relativity
    

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87. Make you a better Rubyist
    

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88. @ work
    

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89. Hiring Filters:
    Write your app in Rails, and enter the hiring fracas. Or,
    use Haskell or Clojure and hire better people with less
    competition.
    — Ben Orenstein
    twitter.com/r00k/status/563821546016636928
    

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90. Bored People Quit
    - Michael Lopp
    randsinrepose.com/archives/bored-people-quit
    

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91. Thoughts + Ideas
    for
    Ruby:
    

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92. RSpec is hard
    

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93. # Ruby
    describe User do
    subject(:user) {
    described_class.new(first_name, last_name)
    }
    let(:first_name) { "Justin" }
    let(:last_name) { "Campbell" }
    it "concatenates a full name" do
    expect(user.full_name).to start_with(first_name)
    expect(user.full_name).to end_with(last_name)
    end
    end
    

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94. # Ruby
    describe User do
    def test_full_name
    user = User.new("Justin", "Campbell")
    assert_equal "Justin Campbell", user.full_name
    end
    end
    

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95. Outside-in?
    Inside-out?
    

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96. Inside-out?
    Outside-in?
    

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97. $ sbt test
    [info] Set current project ...
    [info] Run completed in 397 milliseconds.
    [info] Total number of tests run: 1
    [info] Suites: completed 1, aborted 0
    [info] Tests: succeeded 1, failed 0, canceled 0, ignored 0, pending 0
    [info] All tests passed.
    [success] Total time: 2 s
    

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98. $ sbt ~test
    [info] Set current project ...
    [info] Run completed in 397 milliseconds.
    [info] Total number of tests run: 1
    [info] Suites: completed 1, aborted 0
    [info] Tests: succeeded 1, failed 0, canceled 0, ignored 0, pending 0
    [info] All tests passed.
    [success] Total time: 2 s
    1. Waiting for source changes... (press enter to interrupt)
    

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99. $ rake ~test
    

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100. $ rake ~test
     task :test do |t|
     t.watch /^.+_test\.rb$/
     end
     

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101. $ lein test
     Retrieving lein-exec/lein-exec/0.3.1/lein-exec-0.3.1.pom from clojars
     Retrieving lein-exec/lein-exec/0.3.1/lein-exec-0.3.1.jar from clojars
     Retrieving org/clojure/clojure/1.6.0/clojure-1.6.0.pom from central
     Retrieving org/sonatype/oss/oss-parent/7/oss-parent-7.pom from central
     Retrieving org/clojure/tools.nrepl/0.2.3/tools.nrepl-0.2.3.pom from central
     [...]
     lein test ...
     Ran 1 tests containing 1 assertions.
     0 failures, 0 errors.
     

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102. $ bundle exec rspec
     Could not find rspec-5.0.0 in any of the sources
     Run `bundle install` to install missing gems.
     

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103. $ bundle exec rspec
     The following gems are missing
     * rspec (3.0.0)
     Installing rspec 3.0.0
     Bundle complete!
     ...............
     Finished in 0.16548 seconds
     15 examples, 0 failures
     

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104. # Ruby
     class Animal
     def initialize(type)
     @type = type
     end
     end
     Animal.new(:cat) # => #
     

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105. # Ruby
     class Animal
     def initialize(type)
     @type = type
     end
     end
     Animal(:cat) # NoMethodError
     

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106. # Ruby
     require 'newk/everything'
     class Animal
     def initialize(type)
     @type = type
     end
     end
     Animal(:cat) # => #
     

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108. "Learn a language a year"
     

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109. Too long
     +
     Too short
     

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110. Start Small
     

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111. Pick
     a
     Project
     

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112. URL Shortener
     

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113. Conway's
     Game of Life
     en.wikipedia.org/wiki/Conway's_Game_of_Life
     

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114. Which
     Language
     First?
     

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115. Haskell
     

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116. Clojure
     

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117. Go
     

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118. Fun + Community
     

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119. Fun!
     Compiler + Readability
     

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120. Community!
     Adoption + Friendliness
     

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121. Resources:
     

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123. learnxinyminutes.com
     

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124. !
     github.com/kata-seeds
     

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125. Share
     your
     Excitement
     

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126. Have
     Fun
     

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127. Dude, sucking at something is the first step towards
     being sorta good at something
     - Jake, Adventure Time
     

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128. Thanks!
     @justincampbell
     

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