title: Using a gem in a pure ruby script (not Rails)
body: <p>A ruby file:</p>
  
  <pre><code>gem "my-gem", git: "https://github.com/gem123.git", branch: "some-branch"
  require "my-gem"
  
  var1 = SomeGem::some_method123
  puts var1
  </code></pre>
  
  <p>It says <code>Could not find 'my-gem' (&gt;= 0) among 330 total gem(s) (Gem::LoadError)</code>. Why not? I  need a special branch of a gem and don't want to clone the repository.</p>